To prep:- Take the half-and-half out of the fridge to let it warm up a bit.- Grate your cheeses and add them to a large bowl and toss together. Measure out 4 cups (this is for the sauce) and keep that separate from the remaining 2 cups of cheese (for the middle layer of the mac and cheese).- For the panko topping, melt 1/4 cup of the butter in a medium bowl and set aside (don't add the panko in until step 10). - Add the seasonings (salt, garlic powder, mustard powder, paprika, and pepper) to a small bowl. Preheat the oven to 375F and move the rack to the top third of the oven.
Boil a large, salted pot of water for the macaroni and cook it for 1 minute less than package directions indicate. Once it's done, drain it, add a bit of olive oil or butter to it (less than 1 tbsp) and toss, then set aside (it's fine to sit in the colander you drained it in).
To a pot/Dutch oven, add the remaining 1/4 cup of the butter and melt over medium heat. Once it's melted, add in the flour and stir (I just use a whisk) until combined. Let it cook for 3-5 minutes, stirring fairly often, until it starts to smell a little nutty and goes a bit golden (it should still be pale).
Gradually whisk in the half-and-half. Keep whisking or else it could scorch to the bottom of the pot. Whisk until the sauce gets thick enough to coat the back of a spoon. Timing can vary, and this can take up to 10 minutes or so - be patient and don't stop whisking. Don't let the sauce get too thick - it will get a lot thicker as you add the cheese.
Take the pot off the heat and gradually whisk in the 4 cups of cheese as well as the seasonings (salt, garlic powder, mustard powder, paprika, and pepper).
Add the cooked macaroni to the pot and stir until coated.
Add half the mac/cheese mix from the pot to a 9x13 baking dish and spread it in an even layer. I find it easiest to do this with a ladle.
Sprinkle the remaining 2 cups of cheese into the baking dish, then add the remaining mac/cheese mix on top of it.
Add the panko to the bowl with the melted butter and stir until combined, then sprinkle it over the mac and cheese.
Bake, uncovered, for 15-20 minutes (let the topping turn golden but don't overcook as the sauce will dry out). Enjoy hot!