Preheat your oven to 425°F (220°C). Spread the tater tots evenly on a baking sheet and bake according to the package instructions until golden and crispy.
While the tater tots are baking, cook the breakfast sausage in a large skillet over medium heat, breaking it apart with a spatula until fully cooked. Transfer the sausage to a plate lined with paper towels to drain excess grease.
In the same skillet, melt the butter over medium heat. Sprinkle in the flour and whisk constantly for about 2 minutes to form a smooth roux.
Gradually pour in the milk while continuing to whisk, ensuring no lumps form. Bring the mixture to a gentle simmer and cook until thickened, about 5 minutes. Season with salt and pepper to taste.