1. Heat oven to 350°F. With fork, stir together dry muffin mix and 1 cup water until well blended in 13x9x2-inch baking pan. Stir in applesauce, chocolate chips and peanut butter chips.
2. Stir together brown sugar, remaining 1-1/4 cups water, lemon juice and butter in medium saucepan. Cook over medium heat, stirring constantly, until mixture boils; pour carefully over chip mixture in pan. DO NOT STIR.
3. Bake 35 to 40 minutes or until wooden pick inserted in center comes out clean. Cool slightly; serve warm with whipped topping, if desired. Makes 12 servings.