Mix together in a large bowl:

2 c. flour
2 c. sugar
2 eggs
1/2 tsp. salt
1 tsp. baking soda
1/2 c. yogurt

Bring to boil in saucepan:

2 sticks butter
4 tbsp. cocoa or 1 square
1 c. water

Add to the flour mixture and mix well. Pour into greased jelly roll pan. Bake at 350 degrees for 20 minutes.