Preheat the oven to 350°F. Spray a 9x13-inch baking dish with non-stick cooking spray.

In a large deep skillet, cook the hash browns according to package directions. Arrange the cooked hash browns in the prepared baking dish, creating the bottom layer of the casserole.

Using the same skillet, cook the sausage according to its package directions. Halfway through the cooking time, add the onion and bell peppers. Continue cooking for 2-3 minutes, until sausage is done. Spread the sausage and peppers mixture over the hash browns to form the second layer of the casserole.

For the top layer, sprinkle with cheddar cheese to cover the entire casserole.