Preheat the oven to 350°F. Prepare (butter & flour or spray with non-stick spray) two 8-inch round cake pans.
Sift together the flour, sugar, cocoa, baking soda, baking powder and salt in a large bowl. Set aside.
In a stand mixer add in the sour cream, vegetable oil and eggs. On low speed mix the ingredients together.
Gradually add the dry ingredients into the wet ingredients.
Beat on low until just combined, scraping down the edges as necessary. Be careful not to overmix.
Remove bowl from mixer and fold in the beer.
Divide the batter between the prepared pans and bake for 30 to 35 minutes, or until a cake tester comes out clean.
Cool the cakes in their pans for 10 minutes before carefully turning them out onto a cooling rack.
In a medium bowl add all the confectioners sugar and whisk to remove all lumps. One tablespoon at a time, add in the beer. (A fuller bodied beer will typically add more flavor and color.)
Stir until you reach desired consistency, one that is similar to pancake batter.
Place one cool layer of cake on cake stand.
Drizzle approximately 1/4 cup of Beer Glaze over cake, allowing it to spill over sides.
Place other layer of cooled cake on top and drizzle with remaining glaze.
Cake can be served immediately or refrigerated for 24 hours. Glaze will harden but cake will remain quite moist.