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:
  1. 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.
  2. 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.
  3. 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.)
  4. 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:
  1. 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.)
  2. 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.
  3. Add marshmallow cream and toasted marshmallows, and mix on lowest setting for about 1 minute.
For the Raspberry Buttercream:
  1. 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.
  2. 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.
  3. 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.
  4. 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.
For the Ganache:
  1. 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.
  2. Allow the ganache to cool slightly before pouring over a cake. Start at the center of the cake and work outward.
  3. 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:
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. Add any topping you like or none at all. I sprinkled chocolate jimmies on top, and added one single fresh raspberry.
  8. Get creative!
  9. 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.
Sweetapolita's Notes

*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.