Peanut Butter Cookies

1/2 cup butter
1/2 cup peanut butter
1/2 cup brown sugar
1/2 cup white sugar
1 egg
1-1/2 cups flour
1 teaspoon baking soda
1/4 teaspoon salt
1/2 teaspoon vanilla

Bake at 375-degrees for 12-15 minutes on a greased cookie sheet (I use parchment paper instead).