- 2 tablespoons olive oil
- 1 cup chopped mushrooms
- 1 onion, chopped
- 1 green bell pepper, chopped
- 4 cups frozen shredded hash brown potatoes, thawed
- 2 cups diced cooked ham
- 1 (10.75 ounce) can condensed cream of chicken soup
- 1 cup sour cream
- 1 cup shredded Cheddar cheese, divided
- 1 cup grated Parmesan cheese, divided
- Preheat oven to 350 degrees F (175 degrees C). Grease a 3-quart baking dish.
- Heat olive oil in a large skillet over medium heat; cook and stir mushrooms, onion, and bell pepper in hot oil until onions are translucent, about 5 minutes. Transfer vegetables to a large bowl.
- Stir hash brown potatoes, ham, cream of chicken soup, sour cream, about 3/4 cup Cheddar cheese, and about 3/4 cup Parmesan cheese into vegetables. Spread potato mixture into the prepared baking dish. Sprinkle remaining 1/4 cup Cheddar cheese and 1/4 cup Parmesan cheese over potato mixture.
- Bake in the preheated oven until bubbly and cheese is melted, 40 to 45 minutes. Let stand for 5 minutes before serving.