Cook elbow noodles according to package directions. Reserve 1 cup pasta water, optional. Drain the rest of the water and set aside.
While pasta is cooking, make cheese sauce. In a large saucepan, melt the butter and whisk in the flour at low heat.
Whisk until it takes on a golden brown color, about 2-3 minutes.
Whisk in the mustard and then slowly whisk in the whole milk and heavy cream. Keep whisking until the sauce thickens slightly.
Once the sauce has thickened, add the ground mustard, salt, garlic powder, and cayenne pepper and stir together until combined.
Take the pan off heat and stir in the sharp cheddar and mozzarella cheese.
Whisk together until everything is melted and creamy.
Combine the elbow noodles with the cheese sauce and stir together.
For extra creaminess, add in 1/4 to 1/2 cups pasta water. This works especially well when the mac and cheese starts to cool and thicken. The warm pasta water will bring it back to life without watering down the cheese sauce. This is a completely optional step.
Plate and serve. Best when served warm.
Notes
I like to use a mix of sharp cheddar and mozzarella in this recipe, see my tips above for other cheese options.
Freshly shredded cheese is best.
You can add chicken broth/stock to this to add some more flavor.
Use any of your favorite smaller pasta as long as it equates to the amount used in the recipe.