You are here: Home » Recipes » Baked Idaho Mashed Potato Casserole Baked Idaho Mashed Potato Casserole Recipe by Idaho Potato Commission Yield 6 to 8 servings Tasty mashed potatoes are loaded with cheese, onions and celery and made into a convenient casserole. PrintEmail Ingredients 6 -- red potatoes, cut into quarters2 tablespoons extra-virgin olive oil3 tablespoons butter1/4 cup half and half1 small onion, finely chopped1 stalk celery, finely chopped1/2 cup red pepper, finely chopped3 tablespoons grated Asiago Cheese1/2 teaspoon salt1/4 teaspoon pepper1 pinch paprika Instructions Cook the potatoes in boiling salted water until tender, about 15 minutes. Preheat oven to 450F. Heat 1 tablespoon of olive oil over medium heat in a skillet. Sauté the onions, celery and red pepper until tender. Set aside. When the potatoes are done, drain well and return to the cooking pot. Add butter and half and half. Mash together. Add sautéed vegetables. Season the mixture with salt and pepper to taste. Spread the remaining tablespoon of olive oil in an 8×8 casserole dish. Spoon mashed potatoes into the dish and sprinkle with Asiago cheese and paprika. Bake for 20 minutes or until golden brown.