tbsp butter (divided)
large sweet onions (chopped)
lb red potato (peeled and cubed)
lb sweet potato (peeled and cubed)
cup milk (divided)
cup sour cream
tsp salt (divided)
Preheat 350 degree - Bake 1 hour and 15 minutes Melt 1 tbsp butter in large skillet over medium heat and add onions and sugar. Cook, stirring often 25 minutes or until onions are deep golden brown. Remove from heat and set aside. Meanwhile, place red potatoes and enough water to cover in a large pot, bring to a boil over medium heat. Reduce heat to medium cook 20 minutes or until tender. Drain. Repeat procedure with sweet potatoes. Preheat oven 350 degrees. Spray 3 quart oval baking dish with nonstick spray. Beat red potatoes until mashed. Add 1/4 cup milk, sour cream and 2 tbsp butter, beating until smooth. Stir in 1 tsp salt and pepper. Spoon into baking dish. Beat sweet potato until mashed, add remaining 1/4 cup milk and remaining 2 tbsp butter, beating until smooth. Stir in remaining ½ tsp salt. Spread over the red potato, top with half onion and swirl gently with a knife. Top with remaining onions. Cover and bake for 25 - 30 minutes or until thoroughly heated.