Double Chocolate Mud Bars
["1/2 c. butter, softened", "1 c. granulated sugar", "2 large eggs, separated", "1 1/2 c. all-purpose flour", "1 tsp. baking powder", "1/2 tsp. salt", "1 c. chopped walnuts", "1/2 c. semi-sweet chocolate chips", "1 c. miniature marshmallows", "1 c. brown sugar, packed"]
["Preheat oven to 350\u00b0.", "Grease a 13 x 9-inch baking pan.", "Beat together butter and sugar at medium speed until light and fluffy. Beat in egg yolks, one at a time, until blended.", "Mix together flour, baking powder and salt.", "Fold flour mixture into butter mixture.", "Press mixture into prepared pan.", "Pack down firmly. Sprinkle nuts, chocolate chips and marshmallows over the top of mixture in pan.", "Beat egg whites at high speed until stiff peaks form.", "Fold in brown sugar.", "Spread over mixture in pan.", "Bake for 35 minutes or until a crust is formed.", "Transfer pan to a wire rack to cool completely.", "Cut into squares.", "Makes 36."]
["butter", "sugar", "eggs", "flour", "baking powder", "salt", "walnuts", "semi-sweet chocolate chips", "marshmallows", "brown sugar"]