In a large mixing bowl, cream butter, granulated sugar, brown sugar, and eggs. Add peanut butter and vanilla, and beat 3 minutes, more. Mix in dry ingredients, and stir just until combined. Dump dough onto prepared baking pan, and use a spatula to spread to about 1 centimeter from the edges. Bake at 350 degrees for 20-25 minutes. Cool completely on a wire rack.