Stir melted butter, sugar, and vanilla. add eggs one at a time, beating well with spoon after each addition. add cocoa, beat until well blended. In a separate bowl mix flour, baking powder, and salt until well blended. Add to cocoa mixture until well blended. Stir in nuts if using. Put in 2 miniature cupcake pans sprayed with Pam. Bake at 350 degrees oven, for about 15 min. or a tooth pick comes out clean.