Preheat oven to 350 degrees F. Lightly grease a cookie sheet
. Beat the butter in a mixing bowl for about 1 minute. Add baking powder, salt, and both sugars, and combine. Add egg, vanilla, banana, and flour, mixing well. Stir in the chocolate and nuts. Drop dough by rounded teaspoons about 2 inches apart onto prepared cookie sheet. Bake
at 350F for 25 minutes or until golden. Makes about 36 cookies.