With an electric mixer, combine 1/4 cup sweetened condensed milk, milk, butter, cake mix, and egg white. Mixture will be very thick. Spray 9x13 pan with cooking spray. Press 2/3 of the mixture into the bottom of the pan. Use either floured hands, or spray your hands with cooking spray in order to press it down without having it stick to your fingers. The layer will be thin. Bake for 10 minutes.

Combine 1/2 cup sweetened condensed milk and marshmallow creme in a bowl and combine until smooth. Stir in PB morsels. No one will tell if you stir in some extras.

Spread marshmallow layer over brownie layer in pan. Carefully drop remaining brownie batter by spoonfuls over marshmallow mixture. Bake at 350 for 20-30 minutes. (The original recipe calls for 30 minutes, but many readers have noted that 20 minutes was perfect, and I usually only bake for about 20-25). Remove from oven and cool before cutting into squares.