Beat the butter until creamy, 2 minutes. Add the sugars, beat for 2 more minutes. Mix in the peanut butter and egg. Mix together the dry ingredients - flour, baking soda, baking powder and salt. Stir the dry ingredients into the sugar butter mixture

Wrap dough in plastic and refrigerate at least 3 hours.

Preheat oven to 375°F. Shape dough into 1 1/4 inch balls. Place about 3 inches apart on ungreased cookie sheet. Flatten in crisscross pattern with a fork. Bake until light brown, 9 to 10 minutes. Cool on baking sheets for a minute; transfer to rack to cool completely.

For chewier cookies, bake at 300°F for 15 minutes.