1/2 cup (100g) butter or margarine

2 cups brown sugar

3 eggs

1 teaspoon vanilla

2 teaspoons baking powder

1/2 teaspoon salt

3/4 teaspoon xanthan gum or guar gum (optional)

1/3 cup cocoa

1 1/2 cups GF flour

1 cup chopped nuts (optional)

Blend together. Spread in a 9 x 13 inch pan. (23 x 33 cm pan) Bake at 350F (175C) for 30-35 minutes.