1 pkg. yellow cake mix
1/2 c. butter
2 eggs
1 c. peanut butter (creamy or crunchy)
1 c. chocolate chips
1 can sweetened condensed milk

Mix cake mix, butter, eggs and peanut butter. Pat 2/3 of this mixture in bottom of 9 x 13 inch pan. Melt chocolate chips and condensed milk. Pour chocolate mixture over cake mixture in pan. Pat remaining 1/3 cake mixture on top of chocolate mixture. Bake for 20-25 minutes at 350 degrees. Cool. Cut into squares.