Chewy Peanut Butter Pan Squares

In a microwave-safe bowl, melt butter and peanut butter; stir until smooth. Combine sugar and flour; gradually add to butter mixture and mix well. Beat in eggs and vanilla. , Spread into a greased 13x9-in. baking pan. Bake at 350° until lightly browned and edges start to pull away from sides of pan, 28-32 minutes. Cool on a wire rack.