Preheat your oven to 375°F (190°C). Apply a coat of butter or cooking spray to grease a baking dish, then set it aside.
Prepare the elbow macaroni according to the package instructions, cooking it until it is al dente. Drain the pasta and set aside.
In a medium saucepan, melt the unsalted butter over medium heat. Once the butter is melted, add the flour and whisk continuously to create a roux.Cook the roux for about 1-2 minutes until it becomes slightly golden in color.
While whisking constantly,slowly pour in the milk to avoid lumps forming. Continue to cook the sauce, stirringregularly, until it thickens and coats the back of a spoon. This should takeapproximately 5-7 minutes
Reduce the heat to low and add the shredded cheese to the sauce,reserving a small amount for the topping. Stir the cheese until it iscompletely melted and the sauce becomes smooth and creamy.
Add the Dijon mustard, garlic powder, onion powder, nutmeg (if using),salt, and black pepper to the sauce. Mix well to incorporate the flavors.
Combine the cooked elbow macaroni with the cheese sauce, making sure all the pasta is coated evenly.
Transfer the mac and cheese mixture into the prepared baking dish. Ifdesired, sprinkle the remaining shredded cheese and breadcrumbs on top for a crispyand golden crust.
Bake the mac and cheese in the preheated oven for 20-25 minutes or untilthe top is bubbly and lightly browned.
After baking, take the macand cheese out of the oven and let it cool for a few minutes before serving.