3/4 cup granulated sugar
3/4 cup firmly packed dark brown sugar
2 large eggs
2 squares (1-oz each) sweet dark chocolate, melted, cooled
1 tbsp vanilla extract
2 cups all-purpose flour
1/2 cup unsweetened cocoa powder
1 1/2 tsp baking soda
1/4 tsp salt
1 1/2 cups buttermilk
Preheat oven to 350 degrees.
Grease two 9-inch round cake pans and line with parchment paper; set aside.
In large mixer bowl, beat butter and both sugars with an electric mixer at medium speed until light and fluffy. Add the eggs, 1 at a time, beating until blended after each. Add the cooled chocolate and the vanilla; beat until blended.
Combine the flour, cocoa powder, soda, and salt; add to the buttermilk alternately with the buttermilk, beginning and ending with the flour mixture. Beat at low speed after each addition until blended.
Pour the batter evenly into the prepared pans. Bake at 350 degrees for 22 minutes or until a wooden toothpick inserted in the centers comes out clean. Cool the cakes in the pans on wire rack for 10 minutes. Remove from pans to wire racks to cool completely.