01 -
Let things cool a bit, then cut into squares and dig in while it’s still warm.
02 -
Sprinkle the rest of the cheddar and mozzarella right over the top. Pop it in the oven for 25 to 30 minutes. Spin the dish around about halfway so everything browns nice and even, and bake until the cheese bubbles up and gets a nice deep color.
03 -
Put your cooked spaghetti into the 23 x 33 cm (9 x 13 in) casserole dish. Scatter 1 cup each of cheddar and mozzarella over the noodles. Pour that creamy cheese sauce all over everything, then give it a good mix so each strand gets coated.
04 -
Slowly add your half and half a bit at a time while whisking, then pour in the heavy cream too. Let it boil for a minute, then toss in 2 cups of cheddar and 1 cup of mozzarella. Lower the heat to medium-low. Keep stirring until the cheeses melt right into the sauce.
05 -
Melt your butter in a medium-size enamel cast iron pot on medium heat. Whisk in the flour for just half a minute to make it smooth. Stir in black pepper, cayenne, kosher salt, and garlic powder next.
06 -
Go ahead and start heating your oven to 206°C. Fill a big pot with salted water and get it boiling. Drop in the spaghetti and let it cook for about 6 minutes, then drain it well.