Press down dough from 10-ounce can refrigerated pizza crust in 9 x 13 baking sheet. Prick with fork; bake at 350°F. 15 minutes or till lightly browned. Cool.
Peel and cube 3 large potatoes; cook in water to cover until tender; drain; mash, adding whatever you like - a little salt, about 1/4 cup milk, a little butter. Spread potatoes over crust.
In skillet, partially cook 3/4 to 1 pound diced bacon. Add 1 cup chopped onion and 1/2 cup chopped red and green bell peppers (minced garlic optional) to partially cooked bacon. Finish cooking until bacon is crisp and veggies tender. Drain well. Sprinkle bacon mixture over potatoes; top with 1 1/2 cups shredded Cheddar and 1 1/2 cups shredded mozzarella (or 3 cups Cheddar-mozzarella blend).
Increase oven to 375°F.; bake 20 minutes. Serve with sour cream if desired.
Makes 8 servings.