Preheat the oven to 350 F. Cook pasta according to package directions, drain. Melt the butter in a large saucepan over medium heat. Add in the flour, and cook for a minute to brown.
Add in the milk, salt, pepper, and 2 cups cheese. Continue to cook, while stirring until the cheese has fully melted and the sauce has thickened.
Mix the sauce with the pasta. Spread the mixture into a greased baking dish. Top with 1/2 cup cheese. Top with tater tots and the remaining cheese. Bake for 40-45 minutes.