12 ounces gluten-free pasta (we used this Bionaturae rigatoni)
1 stick (8 tablespoons) unsalted butter
1 cup whole milk
mound of grated cheddar cheese (a little more than a cup for us)
mound of grated gouda cheese (a little more than a cup for us)
2 tablespoons cornstarch
Kosher salt and cracked black pepper
Recipe
Bring a large pot of heavily salted water to rapid boil. Throw in the pasta, along with a glug of olive oil. Cook until the pasta has a slight bite to it. (Gluten-free pasta needs to come out of the water with a little bit of crunch. Cook until it is soft and you will have mush.) Trust your taste instead of the timing on the package. They are usually off. Drain in a colander, toss with a little bit of oil, and set aside.
In the same pot, melt the butter. Add the milk and swirl them together. When you have one bubbly liquid, add handfuls of the cheese and stir. Add more handfuls of the cheese and stir until all the cheese has been melted fully.
I found that using the Gouda instead of the American cheese I used as a kid meant this sauce didn't thicken the way I expected. You could use less milk, or you could do what we did. Make a little slurry with the cornstarch and 2 tablespoons of water. Stir it well, then add a bit into the cheese sauce and stir. The sauce will thicken immediately (you may not need all the slurry).
Season the sauce with salt and pepper. Pour in the pasta. Stir.
You can easily eat the mac and cheese right here. Or, if you want, you can brown it in a 400° oven while you make some broccoli and salad for dinner.