1Heat oven to 375°F. Make potatoes as directed on box, using ovenproof 10-inch nonstick skillet.
2Meanwhile, in another 10-inch nonstick skillet, cook mushrooms, onion and bell pepper over medium-high heat about 5 minutes, stirring frequently, until vegetables start to soften.
3When potatoes are done, sprinkle with cooked vegetables and cheese. In medium bowl, beat eggs and cream with whisk; pour on top.
4Bake about 20 minutes or until eggs are set. Loosen around side of frittata. Carefully turn upside down onto platter, and cut into wedges.