Combine first 3 ingredients in a saucepan; cook over medium heat, stirring constantly, until morsels and peanut butter melt. Remove from heat. Stir in pecans and chocolate crumbs. (Batter will be very thick.) Press batter into a heavily greased 8" square pan. Bake at 350° for 24 minutes. Let cool in pan. Cut into 2" squares.