Chocolate Birthday Cake with Milk Chocolate Frosting

Originally from my cookbook, this is the only birthday cake recipe you will ever need.

Chocolate Birthday Cake with Milk Chocolate Frosting

For the cake: 

2 cups all-purpose flour

2 teaspoons baking soda

3/4  tsp. salt

¾  cups sour cream

1  cups warm water

1 1/3 cups brown sugar (light or dark) 

1 stick (4 oz.) unsalted butter, at room temperature 

3 eggs

1 Tbs. vanilla extract

1 tsp. espresso powder mixed with 1 Tbs. water

4 oz. melted bittersweet chocolate 

For the frosting: 

2/3 cup whole milk

3 large egg yolks

1 tablespoon plus 1 teaspoon all-purpose flour

1 1/3 cups confectioners sugar

1 teaspoon vanilla

2 sticks  unsalted butter, cut into tablespoon pieces and softened

8 oz milk chocolate, melted and cooled

2 oz unsweetened chocolate, melted and cooled

Pre-heat oven to 325°F. Line a 9 x 13 cake pan with parchment paper and spray with non-stick spray. 

In a medium sized bowl combine the flour, baking soda, and salt. Set aside

In another medium sized bowl combine the sour cream and warm water. Set aside. 

In a large bowl cream together the brown sugar and butter until light and fluffy, about 3 to 4 minutes. Add eggs, vanilla and espresso. Mix well. Add melted chocolate and mix until completely combined. 

Alternate adding in the flour and sour cream mixture, starting and ending with the flour mixture.  

Place batter in prepared pan and bake for 40 - 45 minutes or until a toothpick comes out clean.

Let cakes cool completely.

To make the frosting, heat milk in a small pot over moderate heat until warm. 

In a seperate bowl whisk together yolks, flour, 1/3 cup confectioners sugar, and a pinch of salt in a bowl, then add hot milk in a stream, whisking. Transfer custard to saucepan and bring to a boil over moderate heat, whisking. Reduce heat and simmer, whisking, 2 minutes (mixture will be very thick), then transfer to a large bowl. Cover surface of custard with a plastic wrap and cool completely, about 45 minutes.

While the custard cools, melt the milk chocolate and bittersweet chocolate.

Once the custard is cool, add vanilla and remaining cup confectioners sugar and beat on medium until combined well, then increase speed to medium-high and beat in butter, 2 tablespoons at a time, until smooth. Add chocolates and beat until combined well.

Place the frosting on the cake and enjoy!