This mac and cheese dish has lots of cheese and is super creamy and delicious.
Preheat the oven to 400F.
Grease a large oven proof baking dish lightly with butter.
To cook pasta, fill a medium size pot 2/3 of the way with hot tap water. Add 1 teaspoon salt to the water. Bring to a boil over high heat. Add the pasta and stir with a wooden spoon to be sure noodles don't stick to the bottom of the pot.
Always make sure there is lots of water in the pot when cooking any pasta so the pasta has room to roll around while it is cooking.
Turn the heat down, enough to maintain a boil and stir every so often to prevent noodles sticking. Do not cover the pot. After 8-10 minutes, take a piece of pasta out of the water, allow it to cool and do a test for doneness.
Bite into the pasta. If it is too hard to bite or you see a white center, it needs to cook a little longer. When it cooks all the way through it is ready and cooked el dente.
Put the pasta into a strainer. Shake out excess water and put the pot back onto a cool part of the stove.
Butter the baking dish. Set a large, covered pot of salted water over high heat to boil.
Using a wide large saucepan, melt the butter over medium-low heat. Add the flour and whisk to incorporate, making a roux.
Cook, stirring constantly with a silicone spatula or wooden spoons. Cook for 3-4 minutes until the roux in a light golden color.
Gradually add the milk and cream and whisk into combine and incorporate making a bechamel sauce. Turn the heat up to medium-high until it comes to a boil.Watch very carefully, stirring as needed so you do not scorch the bottom. Cook for about 3 minutes, until thickened and coating the back of a spoon. Turn the heat to low.
Stir in the salt, pepper and mustard powder.
Add the cheese in three batches, stirring each one in until incorporated into the sauce. Shut off.
Add the cheese sauce to the pot of cooked pasta and stir in.
Transfer to the prepared baking dish and place into the preheated oven.
Bake 10-15 minutes until hot throughout and the top has turned a golden brown.