Preheat the oven to 350 degrees.
In a large skillet, brown the breakfast sausage with the chopped onions and peppers over medium-high heat, crumbling the meat as it cooks. Cook until the sausage is well browned, and the onion and peppers are tender.
While the sausage cooks, beat together the eggs, milk, salt, garlic powder, black pepper, and half of the shredded cheese.
Add the tater tots to a casserole dish, then spread the sausage mixture evenly over the top, and then pour in the egg mixture.
Place the baking dish in the oven and bake for 45 minutes. Then, add the remaining shredded cheese and place it back in the oven to melt for 5-10 minutes.
Remove the breakfast tater tot casserole from the oven and let it cool briefly, then serve.