Peanut Butter Chocolate Brownies

1/4 cup butter, softened
1/2 cup creamy peanut butter
1 cup light brown sugar
2 eggs
1/3 cup unsweetened cocoa powder
1/3 cup all-purpose flour
1/4 tsp baking powder
1/4 tsp salt
1 cup chocolate chips
1/2 cup chopped walnuts or peanuts

Preheat oven to 350°F. Line a 9x9 inch square pan with alluminium foil. Lightly grease the foil with cooking spry.
Cream together the butter with the peanut butter until smooth. Add the sugar and beat until light and fluffy. Add the eggs, one at a time.
Sift together the flour with the cocoa powder, the baking powder and the salt.
Stir in the butter cream until just combined. Add the chocolate chips and the walnuts (peanuts). Scrape batter in the prepared pan. Bake about 30 minutes in the preheated oven. Cool brownies on a wire rack about 5 minutes. Then slice.