I began to wonder if a buttercream cake would taste even better that way. It really does get difficult to make a buttercream cake look unique, aside from getting too crazy on the inside of the cake, which I tend not to do. I love classic layers, and I love gorgeous fillings, so really, that means getting creative with combinations of the flavours, as well as scale, height, and, well, shape. Aside from the ganache drizzle (which, oops, isn't as smooth as it should be, so we'll talk about that!), all the components of this cake are my trusty standbys: Swiss meringue buttercream, chocolate cake baked in a sheet pan (although I did use a slightly different chocolate cake recipe), and the newest addition, toasted marshmallow filling in place of the raspberry buttercream in the middle layer. To be honest, this cake really doesn't necessarily need any marshmallow representation (amazing, though), but I happened to have some left from a cake I did the other day, and I thought it would be fun to use it to fill one of the layers. It really does work well, and it tastes so good together, but if you were to create this cake, you could most definitely just do all raspberry buttercream, or even just vanilla buttercream, or both. You could even alternate a whipped ganache filling and raspberry buttercream -- trust me, there is no wrong answer here.
Do you think that this cake would taste even better because of its unusual shape, even though all of the parts are the same as some of my round cakes? I don't know why, but I think it does. Slicing into this was so fun, and for some reason, I think square/rectangular dessert tastes better all around, actually. Is it just me, or when you were a kid, wasn't it so exciting to have your ice cream sliced right out of the box (especially neapolitan!) and eat a big square piece of ice cream on a plate? That was the ultimate (is ice cream in the box just a Canadian thing?). Even ice cream sandwiches (speaking of which, I would give anything for one of those right now), cookies, marshmallows, cupcakes, and even pie -- I just came across square pie in the city and loved it. Can you think of any others?
I'm not saying this idea is revolutionary, but I hadn't done it before, and I was thinking this would be a unique way to serve a classic birthday cake, shower cake, or even wedding dessert table cake, or cakes. There are so many gorgeous rectangular platters out there, and you could even build an entire dessert table out of these cakes, all different lengths -- am I getting carried away? Even so, this one really has presence (in my humble opinion) and of course you could build it any way you like, with any flavours, or more or less layers. I'll write the full how-to below, but just to give you an idea of what I did was just bake the chocolate cake in a bakers' half sheet (the same one I use for baking my cookies), and slice it into 4 even slices.
I started with vanilla Swiss meringue buttercream, added about few handfuls of fresh raspberries and some toasted marshmallow filling. Then I just built the cake as I would a round cake, but did it right onto the platter. Once it was all frosted, smoothed, and chilled, I made a ganache to drizzle over the top for a dramatic touch. I then threw on a handful of chocolate sprinkles and one fresh raspberry and trimmed the bottom with more chocolate sprinkles. I'm sorry to say that my ganache was a tiny bit bumpy, but, sadly, I didn't realize that until after I drizzled it.
Well, I suppose that's okay, because now we can talk a bit about that. Ganache, being just a simple (albeit incredibly decadent) pairing of heavy cream and chopped chocolate, does seem pretty easy, but I've learned that it can be sensitive. If you've never made it, don't let that deter you, because it really isn't difficult. I've done it successfully several times with a different ratio, but this time I wasn't so lucky. It's possible, in this case, my chocolate wasn't chopped finely enough or that the cream was too hot; I wondered if that may happen.
I did find a Ganache recipe with a different ratio than my old recipe last night, and made a batch that worked beautifully, so just in case, I'll include that version instead. You could also just make a chocolate glaze, if you'd prefer. Either way, it's still gorgeous and yummy, but I'll be sure to not let that happen again. It actually worked out for the best, because the new ganache recipe is even better, and now I can add that to my repertoire.
Here's the recipe:
Dark Chocolate & Raspberry Buttercream Cake with Ganache Drizzle
For the Sheet Cake:
- 2-1/2 cups + 1 tablespoon (330 g all-purpose flour)
- 3 cups 600 g granulated sugar
- 1 cup + 1 tablespoon (135 g Cacao Barry Extra Brute Cocoa Powder (or similar premium brand))
- 1 tablespoon 15 g baking soda
- 1-1/2 teaspoons 7.5 g baking powder
- 1-1/2 teaspoons 12 g salt
- 3 eggs (at room temperature)
- 1-1/2 cups 360 mL buttermilk, room temperature
- 1-1/2 cups 360 mL strong black coffee, hot
- 3/4 cup 180 mL vegetable oil
- 1-1/2 tablespoons 22.5 mL pure vanilla extract
For the Filling:
- 8 large white marshmallows
- 1/2 cup 63 g icing sugar (confectioners' or powdered), sifted
- 1/2 cup butter (113 g(1 sticks), at room temperature)
- 1/4 teaspoon 1.25 ml pure vanilla extract
- 1/2 jar (107 g marshmallow cream (such as Marshmallow Fluff))
For the Raspberry Buttercream:
- 10 large (fresh egg whites)
- 2 1/2 cups 500 g sugar
- 3 cups 680 g butter, cut into cubes and cool, but not cold
- 1 tablespoon pure vanilla extract
- 1/4 cup 59 ml(or to taste) raspberry puree OR a handful (about 1 cup, or more to taste) of fresh, washed, and dried raspberries
- pinch of salt
- few drops pink food colouring (optional)
For the Ganache:
- 9 oz bittersweet chocolate (chopped)
- 1 cup heavy cream
For the Sheet Cake:
- Preheat oven to 350° F. Coat the bottom & edges of a commercial baking sheet (bakers half sheet 13 x 18 x 1) with butter then add a layer of parchment paper to the bottom. Dust it all with flour, tapping out the excess.
- In bowl of electric mixer, sift all dry ingredients. Combine eggs, buttermilk, coffee, oil and vanilla in a measuring cup and beat lightly with a fork.
- Add milk mixture to the dry ingredients mix for 2 minutes on medium speed (you may need the plastic splash-guard that comes with mixer). Divide batter evenly among prepared pan. (Batter will be thin.)
- Bake for 20 minutes and rotate pan. Continue to bake until toothpick or skewer comes almost clean (a few crumbs), about 5 more minutes. Cool on wire rack in pan until completely cool.
For the Filling:
- Place marshmallows on cookie sheet lined with parchment paper and sprayed with nonstick cooking spray. Place on lower rack of oven, and broil marshmallows until nice and brown on top, between 30-60 seconds. Remove pan from oven and gently turn the marshmallows over, and broil until they are golden brown. (Be sure to keep an eye on them--they burn very quickly.)
- In an electric mixer fitted with paddle attachment, combine butter and icing sugar on low until blended, about 1 minute. Add vanilla and mix on med-high for about 3 minutes.
- Add marshmallow cream and toasted marshmallows, and mix on lowest setting for about 1 minute.
For the Raspberry Buttercream:
- Wipe the bowl of an electric mixer with paper towel and lemon juice, to remove any trace of grease. Add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly but gently, until temperature reaches 160°F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot.
- With whisk attachment of mixer, begin to whip until the meringue is thick, glossy, and the bottom of the bowl feels neutral to the touch (this can take up to 10 minutes or so). *Don't begin adding butter until the bottom of the bowl feels neutral, and not warm.
- Switch over to paddle attachment and, with mixer on low speed, add butter cubes, one at a time, until incorporated, and mix until it has reached a silky smooth texture (if curdles, keep mixing and it will come back to smooth). *If mixture is too runny, refrigerate for about 15 minutes and continue mixing with paddle attachment until it comes together. Add vanilla and salt, continuing to beat on low speed until well combined.
- Add raspberry puree to taste or the fresh raspberries in small increments, and blend until combined. Add small amount of pink food colouring, if desired - try a few drops of Sweetapolita Bright Pink!
For the Ganache:
- Place the chocolate into a medium bowl. Heat the cream in a small sauce pan over medium heat. Bring just to a boil (watching very carefully) then swiftly remove from the heat and pour over the chopped chocolate. Let sit for 1 minutes and then whisk until smooth.
- Allow the ganache to cool slightly before pouring over a cake. Start at the center of the cake and work outward.
- For a fluffy frosting or chocolate filling, allow it to cool until thick, then whip with a whisk until light and fluffy.
Assembly of the Dark Chocolate & Raspberry Buttercream Cake:
- Chill sheet cake in freezer for 30 minutes, or refrigerator for several hours. The cake will be a bit sticky, but should not be soft and fragile. If so, place in freezer or refrigerator again until more firm.
- Using a sharp, serrated bread knife, cut the cake in half, then those halves in half--4 total. The pieces will be 11" long and about 4.5" wide.
- Place 1st layer face-up (on a platter, or whatever you choose to serve the cake on), and spread about 1/2" thick layer of buttercream on top. Repeat this step, adding any flavours of buttercream or filling you like, placing your final layer face down. Cover with plastic wrap loosely, and chill for about 15 minutes in freezer or 30 minutes in refrigerator.
- Crumb Coat Coat cake with thin layer of buttercream using a small offset spatula for the top and a straight offset spatula for the sides--if you have a metal bench scraper, you can run along cake to get smooth finish and to achieve sharp corners. Always start at the top of the cake, working your way down. Chill cake for about 30 minutes, or pop back in freezer for 10-15 more minutes to set buttercream. This is a good time to wash and dry your spatulas and bench scraper for the top layer of buttercream application.
- Using your clean tools, add a thick layer of buttercream on the top of the cake, working it over the edges and then finish the sides. Be very generous with your buttercream, because you will be scraping most of it off with the scraper. It just makes it so much easier to get the smooth finish. Chill the cake for as long as you need, but at least 15 minutes to set the buttercream.
- Drizzle your warm (but not hot) ganache over the top of your very chilled cake so it seeps down the sides. Be careful not to use too much, or you will lose your pink cake underneath! You can use your clean small offset metal spatula to smooth it over the top. Chill to set.
- Add any topping you like or none at all. I sprinkled Chocolate Crunchy Sprinkles on top, and added one single fresh raspberry.
- Get creative!
- Keep refrigerated, but serve room temperature. Leave out of refrigerator for about 2 hours prior to serving. Keeps up to 3 days in an airtight container, although, I've been known to eat it past that and it was still great.
*The filling recipe is enough to fill the middle layer of this cake.
**For the Raspberry Buttercream, add about a 1/2 pint of fresh washed & dried raspberries if you like the textured effect, or raspberry puree for a smooth finish. *Be sure to add the raspberries right before you are to frost the cake, otherwise, if you store in refrigerator overnight, the moisture of the berries will turn your buttercream into an icky mess.
***You can also add a drop or 2 of pink gel colour to get a pinker look.
****Keep in Raspberry Buttercream in an airtight container in refrigerator for up to one week, leaving out at room temperature when needed, rewhipping in mixer for 5 minutes. You can freeze for up to 6-8 weeks. To thaw, place on counter overnight, and rewhip for 5 minutes with paddle attachment in an electric mixer.
