Chocolate Sour Cream Sheet Cake with Half and Half frosting

 2 cups sugar

1 c. butter

2 c. flour

1/4 c cocoa powder

1 t. baking soda

1 c. water

1/2 t. salt

2 eggs

1/2 c. sour cream

Preheat oven to 350. Grease 12x17 in. jelly roll pan

Stir the sugar, flour, baking soda, and salt in large bowl of an electric mixer.  Add the eggs and sour cream and beat on low speed until blended.  

Melt butter in a saucepan over medium heat.  Add the cocoa adn water, increase the heat, and bring to a boil.  Remove from heat and gradually add the hot mixture to the batter in the bowl, mixing on low speed to combine thoroughly; do not overmix. 

Pour the batter in the prepared pan. Bake for 20 min, or until the toothpick comes out clean.  While cake is baking, make frosting.  Remove the cake from oven and cool in pan for 10 min.  Frost cake.  

Frosting: 

1 stick butter

1/4 c. plus 2 T. milk

1 t. vanilla

6 c. powdered sugar

2 T. cocoa powder

Melt butter in medium pan over medium heat.  Add the milk and bring mixture to a boil.  Remove from heat.  Add the vanilla and powdered sugar. Beat with wooden spoon until smooth.  Add milk if necessary for desired spreading consistency.  

Spread half the frosting on the cake.  

Add the coca to the remaining frosting.  Spread this on other half of cake.