Pre-heat oven to 350 degrees. Line 2 muffin pans with cupcake wrappers. Because this recipe makes so many cupcakes, you will need to bake the cupcakes in two batches or cut the recipe in half.
Put beer and butter into a medium large saucepan. Heat over medium heat until the butter has melted and the mixture starts to simmer.
Take off the heat and stir in cocoa powder. Set aside to cool for a few minutes.
In a separate large bowl, beat together eggs and sour cream.
Slowly pour in cooled chocolate mixture. Beat to combine. Beat in sugar.
Add in baking soda and flour and mix by hand until just combined.
Divide cupcake batter into the cupcake pan.
Bake at 350 degrees for 15-20 minutes. Remove from oven. Allow to cool in muffin pan for about 5 minutes then take the cupcakes out of the muffin pan to finish cooling on cooling rack.
Frost as desired.
Notes
This is a runny batter. Don't worry, it will bake up just fine.