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1
Preheat oven to 350F. Grease two 9-inch round cake pans, and line the bottoms with parchment paper.
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2
For the cake:
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3
In a large bowl, whisk the flour, baking powder, baking soda and salt. Set aside.
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4
In another bowl, whisk the boiling water, chocolate and cocoa powder until smooth.
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5
Beat butter and sugar together on medium speed in a bowl of a standing mixer until light and fluffy. Beat in eggs, one at a time. Beat in sour cream and vanilla extract.
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6
Reduce the speed to low and beat in 1/3 of the flour mixture, followed by half of the chocolate mixture. Repeat with another 1/3 of the flour mixture and the remaining chocolate mixture. Beat in the remaining flour mixture until just incorporated.
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7
Divide the batter and pour into the prepared pans, smoothing the surface with a spatula. Bake 20 to 25 minutes or until a toothpick inserted into the cake comes out clean.
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8
Place the cakes (in the pans) on a wire rack to cool. Then once cooled, invert the cakes onto a greased rack. Cool completely before frosting.
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9
To prepare the buttercream, put egg whites and sugar in a mixing bowl over a pot of simmering water. Use an electric hand mixer to beat constantly until the sugar has completely dissolved and the egg whites are hot. Remove from heat.
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10
With whisk attachment, continue whipping the mixture in a standing mixer until thick, glossy, and cool.
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11
Switch over to paddle attachment. While mixing on medium speed, continuously add softened butter in chunks until incorporated, and mix until it has reached a silky smooth texture. If it appears to curdle, keep mixing and it will come back to smooth. Add vanilla and salt, mix well.
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12
Right before frosting the cake, add the food coloring and raspberries into the buttercream and beat for another 10 seconds, or until the color are evenly distributed.
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13
To assemble the cake, place one cake layer on your serving plate and spread the top with 1/3 of the buttercream. Place the other cake layer on top, and gently press down a little bit. Spread with another 1/3 of the buttercream. Smear the remaining 1/3 of the buttercream on the sides of the cake, and garnish with the remaining raspberries.
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14
Cover and refrigerate the cake. Leave out in room temperature for at least an hour prior to serving.
