Melt 1/4 cup butter in a large Dutch oven over medium-low heat. Add marshmallows, stirring until melted. Remove from heat. Stir in 1 1/2 tsp. vanilla extract. Add orange cake mix, blending well. Stir in cereal and white chocolate morsels until well coated. Spread mixture into a lightly greased 13- x 9-inch pan. Cool completely (about 30 minutes). Meanwhile, stir together powdered sugar, 6 Tbsp. softened butter, orange juice, 1/4 tsp. vanilla extract, orange extract, and desired amount of peach food coloring gel. Spread over cereal mixture. Let stand 1 hour before cutting.