Steps
1. Preheat oven to 350°F (175°C).
2. In a medium bowl, mix together the butter, cocoa powder, sugar, flour, baking powder and salt.
3. Stir in the chocolate chips and nuts.
4. Add the egg and mix until combined.
5. Spread the batter into a greased 8x8 inch baking pan.
6. Bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean.
7. Let cool before cutting and serving.