Chocolate Brownie Cupcakes

So I was trying a new chocolate cupcake recipe. When I took them out of the oven they were more like brownies. They were a delicious surprise!!

I used a recipe from the Primrose Bakery for both the cupcake and the buttercream, however I did add more butter and less powdered sugar.

Cupcakes:
4 oz bittersweet chocolate
6 tbsp butter
3/4 c packed light brown sugar
2 large eggs separated
1 1/4 c all-purpose flour
3/4 tsp baking powder
3/4 tsp baking soda
Pinch of salt
1 c 2% milk
1 tsp vanilla

Preheat oven to 375
Melt chocolate in microwave or in double boiler
Beat butter and sugar until fluffy
Beat egg yolks in separate bowl for several minutes
Slowly add egg yolks
Add melted chocolate
Sift dry ingredients together
Add vanilla to milk
Alternate adding dry ingredients and milk to the butter batter, starting and ending with dry ingredients
Beat egg white in a separate bowl until soft peaks form
Fold egg whites into batter
Bake for 18-22 minutes
Let cool for 10 minutes before removing to wire rack

Buttercream Frosting:
6 oz bittersweet chocolate
1 c (2 sticks) butter
1 tbs milk
1 tsp vanilla
2 1/2 c powdered sugar

Melt chocolate in microwave o in double boiler
Beat butter, powdered sugar, milk and vanilla
Add chocolate and beat until thick fluffy consistency, this can take up to 10 minutes

**I used 3 sticks of butter and only 2 cups of powdered sugar