In a mixing bowl combine the butter, peanut butter, brown sugar, corn syrup and vanilla. Gradually add the oats. Press into a greased 13x9 inch pan. Bake @400 for 12-14 minutes or until golden brown. Cool for 5 minutes --
Melt chips and peanut butter in a microwave or saucepan. Stir until blended. Spread over bars. Cool completely. Refrigerate for 2-3 hours before cutting.