In 12-inch skillet, cook sugar over medium heat, stirring constantly, until melted and golden. Remove from heat; place remaining 3/4 cup walnuts in sugar mixture, turning to coat. With fork, remove walnuts to waxed paper; cool completely. Into large microwavable bowl, spoon 2 containers frosting. Microwave on Medium (50%) 30 seconds or until melted; stir until smooth. Stir in remaining 1 teaspoon maple flavor. Remove several cake balls from refrigerator at a time. Dip tip of 1 lollipop stick about 1/2 inch into melted frosting and insert into 1 cake ball. Dip cake ball into melted frosting to cover; tap off excess. Top with sugared nuts.