1) For frosting, combine scream and chocolate in a saucepan over low-medium heat and cook, stirring constantly, until cream and chocolate is smoothly combined. Don’t boil the mixture, but it should be steaming hot.
2) Remove from heat and let cool in the fridge, stirring occasionally to keep it smooth, for 90-120 minutes.
3) For cakes, combine stout and butter in a sauce pan and put over low-medium heat until butter is melted.
4) Then whisk in cocoa powder. It’s a lot of cocoa powder, so work slowly and make sure the mixture is nice and smooth. Remove from heat and let cool.
5) Whisk dry ingredients (sugar, flour, salt, baking soda) together.
6) Whisk eggs and sour cream in a large bowl. Once smooth, whisk in butter/stout/cocoa powder mixture. Again, whisk until smooth.
7) Whisk in dry ingredients in a few batches. Try not to overmix the batter, but make sure all the flour is incorporated.
8) Pour batter into three round cake tins that have been buttered and floured.
9) Bake for 30-35 minutes at 350 degrees.
10) Cool on a wire rack when the cakes are done. After a few minutes, remove cakes from tins and let cool completely.
11) Use a large knife to slice off the tops of the cakes, making them level.
12) Stake cakes with 1/4 of frosting in between each layer, using the last 1/2 to frost the top and around the sides of the cake.
13) Shave on some fresh chocolate if you want or just serve it up!