Place pumpkin in a large saucepan; add water to cover. Bring to a boil. Reduce heat; cover, uncovered, for 20-25 minutes or until tender.

Meanwhile, place potatoes in another saucepan; add water to cover. Bring to a boil. Reduce heat; cook, uncovered, for 10-15 minutes or until tender.

Drain potatoes; return to pan. Mash potatoes, adding 1/4 cup milk, 4 tablespoons butter and 1/2 teaspoon salt. Add additional milk if needed to reach desired consistency. Transfer to a serving bowl; keep warm.

Drain pumpkin; return to pan. Mash pumpkin, gradually adding the remaining butter and salt and enough remaining milk to reach desired consistency; spoon evenly over potatoes. Cut through mashed vegetables with a spoon or knife to swirl. Drizzle with olive oil; sprinkle with pepper. Serve immediately. Yield: 8 servings.