PREHEAT oven to 350° F.
PLACE potatoes on microwave-safe plate. Microwave on HIGH (100%) power for 15 minutes or until potatoes are tender. Cool slightly; place in large bowl. Add pumpkin, sugar, butter, salt and pepper. With potato masher, smash until lumpy (cut any large pieces of skin into smaller pieces). Add eggs; smash until incorporated. Spoon into 13 x 9-inch or 3-quart baking dish.
COMBINE sugar, flour, butter and salt in small bowl; stir until combined. Sprinkle evenly over casserole; top evenly with nuts.
BAKE for 25 minutes or until golden and heated through. Remove from oven.
PREHEAT broiler. Broil casserole for 1 minute or until bubbly and nuts are toasted. Cool for 5 minutes before serving.