Chocolate, chocolate everywhere! I was looking through some older posts the other day, and I came across these Chocolate Birthday Cupcakes with Nutella Cloud Frosting. And while I've never been fixated on Nutella desserts, I had almost forgotten how much I loved the way the sweet and hazelnutty flavour and creamy texture of Nutella added a much-welcome addition to these otherwise classic (but awesome) chocolate cupcakes. So this week I decided to make a super-simple, quick and easy cake version of those cupcakes, embracing quality dark chocolate, extra dark cocoa powder and, of course, Nutella.Simply put, the frosting is magical. Like unicorn and rainbows magical. I have this thing about chocolate frosting. I kind of need it to be airy and satiny, as opposed to super-fudgy and dense--I think it pairs so well with a deep, dark moist chocolate cake, such as this one. This frosting is a take on that same Nutella Cloud Frosting I had used on the cupcakes, but I decided to add much more Nutella and a generous amount of sour cream to balance out the sweet. Rather than using the mixer, I just popped everything into my food processor and gave it a 60-second spin or so. The result was the creamiest and richest sweet chocolate frosting I've ever tasted. In addition to the Nutella, we add a good dose of extra dark premium melted chocolate (I used a 70%) to help keep some of the intense chocolate flavour. The Nutella lends to the satiny texture, but because it is already quite sweet, the overall quality of this frosting is on the sweet side, but with a dark decadence. If you can't get Nutella, or if you find you prefer a deeper flavour with minimal sweetness, you could even skip the Nutella and add a handful of ground hazelnuts. Of course the texture would change to a more rustic one, but the taste would be notably more sophisticated.But Nutella seems to bring a nostalgic element for some, and if this cake is going anywhere near a little cakelet's belly, I think Nutella is the way to go, because kids go, well, nuts for this stuff. And because this cake, as simple as it is, is a celebration of chocolate, I opted for a medley of chocolate sprinkles as the finishing touch. It adds an interesting visual and delightful chocolaty crunch to each slice. For the piped border, I went with an unfussy shell-style border, but extended each one for a few extra seconds to create a more elongated shell look. Nothing fancy, but quick, easy and pretty. Because this frosting pipes like a dream, it makes for the perfect frosting border.So this photo just goes to show that not all cakes look picture-perfect when sliced (this is what happens when I frost a cake and take photos 10 minutes later, rather than refrigerating it for some time to set), but holy Easter-bunny this chocolaty madness is divine. And it couldn't be easier to create. You'll see! Best-Ever Chocolate & Nutella Layer CakeSuper-moist, dark chocolate cake filled and frosted with satiny dark chocolate & Nutella sour cream frosting and covered in a medley of chocolate sprinkles.For the Cake:2 1/4 cups 285 grams all-purpose flour2 1/3 cups 470 grams superfine sugar3/4 cup 90 grams dark Dutch-process cocoa powder (I use Cacao Barry Extra Brute)2 1/2 teaspoons 12 grams baking soda2 teaspoons 10 grams baking powder1 teaspoon 8 grams salt1 1/4 cups 300 ml buttermilk3/4 cup 180 ml brewed coffee or espresso2/3 cup 160 ml vegetable oil3 eggs (room temperature)1 tablespoon 15 ml pure vanilla extractFor the Frosting:4 1/2 cups 565 grams confectioners' sugar1 1/2 cups 340 grams unsalted butter, room temperature1 cup 280 grams Nutella (or other hazelnut spread)3/4 cup 180 ml full-fat sour cream11 ounces 330 grams best-quality dark chocolate, melted and cooled slightly1 tablespoon 15 ml pure vanilla extractPinch of saltFor the Cake:Preheat oven to 350° F. Prepare three 7-inch round cake pans with nonstick spray and parchment rounds.In bowl of electric mixer fitted with the whisk attachment, sift all dry ingredients, including sugar. 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 1 minute on medium speed (you may need the plastic splash-guard that comes with mixer). Divide batter evenly among prepared pans--each pan should contain about 600 grams of batter.Bake the first 2 layers for 20 minutes and rotate pans in oven. Continue to bake until toothpick or skewer comes almost clean (a few crumbs), about 5 more minutes. Cool on wire racks for 20 minutes. Repeat with remaining layer, and then gently invert onto racks until completely cool.For the Chocolate Frosting:Put all of the ingredients in a food processor, and pulse until smooth and glossy, about 1 minute. The frosting will be very soft. Refrigerate the frosting until it thickens slightly, about 15 minutes.Assembly of the Best-Ever Chocolate & Nutella Layer Cake:Put a dollop of frosting on a 7-inch round cake board (or cake plate) or 8-inch scalloped cake board.Put your first layer top-up on the cake board or plate, and spread about 1 cup of frosting evenly across layer. Put the second cake layer on top and repeat with another layer of frosting. Put the final cake layer top-down. Cover the cake with plastic wrap and wiggle the layers into place. Refrigerate the cake for about 30 minutes.Using a turntable, if possible, frost entire outside of cake with a thin layer of frosting to seal in the crumbs. Chill until the frosting begins to firm-up, about 15 minutes. Repeat with another thin layer of frosting, this time working to achieve a smooth finish. Chill for another 15 minutes.Apply a third coat of frosting to the cake. Holding a tall pastry comb in your dominant hand, press it gently against the side of the cake and keep it steady. Use the other hand to slowly rotate the turntable until you have gone all the way around the cake. Gently press some chocolate sprinkles around the bottom edge of the cake.Fit a medium pastry bag with a medium-large closed star tip, such as 1M, and fill about 2/3 full with frosting. Pipe a border around the top of the cake. Chill the cake until the frosting border firms up, at least 30 minutes.Cover the top of the cake (but not the piped border) with chocolate sprinkles. Once frosting softens again, the sprinkles will adhere to top. The cake will keep refrigerated for up to 3 days.Sweetapolita's Notes:If you don't have 7-inch round cake pans, you could also use 8-inch cake pans. The layers will just be ever-so-slightly shorter.For the cake layers, I use Cacao Barry Cocoa Powder - Extra Brute--it adds so much depth, chocolate-y flavour and a wonderfully dark hue.For the frosting I used Callebaut Dark Callets 70.4 % to balance the sweetness of the Nutella.I used one of the Wilton Decorate Smart 3-Piece Icing Comb Set for the sides of the cake (the furthest comb to the right in the image).I love these Chocolate Crunchy Sprinkles for all things chocolate! But you could also try topping with Rainbow Bit Chips or Rainbow Crunchy Sprinkles for a more colourful option.Because the frosting has sour cream in it, it's best to refrigerate this cake if it hasn't been gobbled up after a day. Keep refrigerated at that point, and serve at room temperature (although it tastes pretty great cold too).Happy Easter to you and your family! Good luck & enjoy!