- Cook the macaroni: Bring a large pot of salted water to a boil. Add elbow macaroni and cook until just al dente. Drain and set aside. 
- Make the roux: In a saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1 minute to form a paste. 
- Add milk: Gradually whisk in the warm milk. Cook, stirring constantly, until the mixture thickens, about 3–4 minutes. 
- Melt the cheese: Lower the heat and stir in the shredded cheddar cheese, salt, pepper, and optional dry mustard or paprika until smooth. 
- Combine pasta and sauce: Toss the cooked pasta with the cheese sauce until fully coated. 
- Bake: Transfer everything to a buttered 9x13-inch baking dish. Bake at 350°F for 20–25 minutes, until bubbly and slightly golden. 
- Serve: Let rest for 5 minutes, then serve warm and enjoy the cheesy goodness!