3/4 c. butter, softened
3/4 c. packed brown sugar
3/4 c. granulated sugar
1 tsp. vanilla
2 eggs
1 3/4 c. unsifted flour
1/2 c. baking cocoa
1 tsp. baking powder
1/2 tsp. baking soda
1 (8 oz.) container plain yogurt, room temperature

FROSTING:

1/4 c. butter
1/4 c. baking cocoa
1 1/2 c. powdered sugar
3 tbsp. milk
1/2 tsp. vanilla

Combine butter, sugars, and vanilla. Add eggs, one at a time, beating until mixture is light and fluffy. Combine dry ingredients. Add to creamed mixture in thirds alternately with yogurt. Pour into greased and floured loaf pan. Bake at 350 degrees for 65 to 75 minutes or until cake springs back when lightly touched (top may be cracked). Cool in pan 10 minutes. Invert onto wire rack and cool completely. Frost.

Frosting: Melt butter. Combine with cocoa, sugar, milk, and vanilla. Beat until smooth and creamy, adding additional powdered sugar (if necessary) for spreading consistency.