Makes: 32 pieces. Prep: 25 minutes. Bake: at 350 F for 1 hour, 30 minutes.
Heat oven to 350°F. Line 13 x 9-inch baking pan with foil sheets, extending up the long sides and over short ends.
Mix 1-1/2 cups flour, 1 tablespoon cocoa, 3/4 teaspoon baking powder and 1/2 teaspoon salt in a bowl. Beat 6 tablespoons butter, brown sugar and vanilla in a medium-size bowl until creamy. Beat in 2 eggs, one at a time. On low, beat in flour mixture. Stir in peanuts. Spread into pan; level top.
Beat cream cheese in a medium-size bowl on medium speed until smooth. Add 2/3 cup sugar, 2 eggs and 1/3 cup flour and beat to incorporate. Place mixture in large plastic bag; snip off end. Pipe over blondie layer to cover, gently spreading to smooth top.
Stir 1-1/2 cups flour, 6 tablespoons cocoa, 2 teaspoons baking powder and 1/2 teaspoon salt in a medium-size bowl. Beat 1/2 cup butter and 1-1/3 cup sugar in second bowl until light and fluffy. Beat in 2 eggs one at a time. Beat in peanut butter until well blended. On low speed, beat half flour mixture, then half milk, into butter mixture. Repeat. Place mixture in large plastic bag; snip off end. Pipe over cheesecake layer to cover, gently spreading to smooth top. Place foil tent over top, crimping edges. Do not let foil touch top of batter.
Bake at 350°F, covered, for 1 hour; remove foil and bake 25 to 30 more minutes. Place on rack to cool 30 minutes. Refrigerate at least 2 hours or up to 24 hours.
Prepare 2 packages (2.8-ounces each) chocolate mousse mix as packages direct, using 1 cup milk total. Spread smoothly onto top of bar. Cut into 32 pieces. In a small bowl, combine 1/3 cup chopped dry-roasted peanuts and 1/3 cup chopped chocolate chunks. Stir in 3/4 cup prepared caramel topping. Spoon over individual pieces and serve.