Beat together melted butter, sugars, vanilla, peanut butter, and eggs. In a separate bowl, combine flour, baking soda, bran, and rolled oats. Stir dry ingredients into the butter mixture. Drop peanut butter cookies by teaspoonfuls onto ungreased baking sheet.
Bake peanut butter cookies at 350° for 15 to 18 minutes. Remove to a rack to cool.
Makes 3 to 4 dozen