Pre-heat oven to 350
Cream margarine and sugar.
Add eggs one at a time.
Mix together flour, baking powder, and salt, then mix with the other ingredients. If making the cocolate version, add those ingredients to the flour mixture.
Pour all but 1 c of batter into greased 9×13 pan. Spread filling evenly and dot spoonfuls of remaining batter on top.
Bake at 350 for 35 to 40 minutes.
Source: Rose Ritter, chocolate version by Elizabeth for Dan's 40th birthday