Preheat oven to 350 degrees. Grease the edges of two 8-inch round cake pans. Dust with flour and tap out the excess. Line the bottom of each pan with a circle of parchment paper. Combine the flour, sugar, cocoa powder, baking soda, baking powder, and salt in the bowl of an electric mixer fitted with a paddle attachment. Mix until combined.
Add the egg whites and sugar to the bowl of an electric mixer. Set the bowl over a pot of simmering water. Whisk constantly until sugar is dissolved and temperature reaches 160 degrees on an instant read thermometer. Place bowl on mixer stand and whisk on low speed until mixture is foamy. Increase speed to medium-high and whisk until stiff, glossy peaks form and mixture is cooled completely, about 10 minutes. Switch to paddle attachment, reduce speed to medium-low, and add butter 2 tablespoons at a time, mixing after each addition until incorporated. Mix in salt, vanilla and raspberry puree.
In an electric mixer fitted with the paddle attachment, beat butter on high speed until fluffy, about 2-3 minutes. Add cocoa, sugar and salt and beat until incorporated. Add cream one tablespoon at a time and beat until well incorporated.
Place one cake layer on a cardboard cake round. Spread raspberry buttercream filling over the cake. Top with second cake layer. Frost the top and sides of the cake with the chocolate frosting. Garnish with fresh raspberries as desired.
*Nutritional information is an estimate. Please consult a doctor or nutritionist for the most accurate nutritional info.