1. Prepare: Separate 1 cup of grated mild cheddar cheese from your total supply and set it aside to use for the top layer later.

2. Boil: Cook 2 cups of uncooked elbow macaroni in a large pot of salted boiling water according to the package directions.

3. Rinse: Drain the cooked pasta thoroughly in a colander and rinse well with cold water to stop the cooking process.

4. Transfer: Pour the drained macaroni into a 3-quart casserole dish and set it aside.

5. Melt: Place 1/2 cup of butter in a saucepan over medium heat until melted, then stir in 1/2 cup of flour to form a smooth roux.

6. Whisk: Gradually stir 1 1/2 cups of milk and 1 1/2 cups of sour cream into the flour mixture.

7. Season: Add 1 teaspoon of salt and 1/2 teaspoon of black pepper to the saucepan to season the mixture.

8. Thicken: Cook the mixture over low heat, stirring constantly, until the sauce begins to bubble and thickens.

9. Incorporate: Add 1 cup of grated mild cheddar cheese to the hot sauce and stir until the cheese completely melts.

10. Combine: Pour the finished cheese sauce directly over the macaroni in the casserole dish and mix everything thoroughly.

11. Sprinkle: Scatter the remaining 1 cup of grated mild cheddar cheese evenly over the top of the macaroni mixture.

12. Bake: Place the dish in your preheated 350°F oven and bake for 1 hour until the top is browned and bubbly.

13. Enjoy: Serve this rich, comforting dish hot straight out of the baking dish.