Cook breakfast sausage in a skillet over medium heat until browned and crumbled, about 8 minutes. Drain excess grease.
Grease a 9x13-inch baking dish. Spread cooked sausage evenly in the bottom, then sprinkle with diced bell pepper and 1 cup of the cheese.
Arrange frozen tater tots in a single layer over the top, covering the entire surface.
In a large bowl, whisk together eggs, milk, sour cream, onion powder, salt, pepper, and paprika until smooth.
Pour egg mixture evenly over the tater tots, then sprinkle remaining 1 cup cheese on top.
Cover tightly with aluminum foil and refrigerate overnight or for at least 8 hours.
When ready to bake, preheat oven to 350°F and let casserole sit at room temperature for 15 minutes.
Bake covered for 35 minutes, then uncover and bake for an additional 15-20 minutes until tater tots are golden and crispy and eggs are set.
Let cool for 5-10 minutes before cutting and serving.