01 -
Preheat oven to 206°C. Bring a large pot of salted water to a boil and cook spaghetti for 6 minutes, then drain.
02 -
Melt butter in a medium enamel cast iron pot over medium heat. Add flour and whisk for 30 seconds until smooth. Stir in kosher salt, black pepper, cayenne, and granulated garlic.
03 -
Slowly whisk in half and half in three additions, then add heavy cream. Bring mixture to a boil, add 225 g (2 cups) cheddar and 115 g (1 cup) mozzarella, reduce heat to medium-low, and stir until cheese has fully melted.
04 -
Place cooked spaghetti in a 23 x 33 cm (9 x 13 in) casserole dish. Sprinkle 115 g (1 cup) mozzarella and 115 g (1 cup) cheddar over pasta. Pour cheese sauce evenly over the top and stir to fully combine.
05 -
Distribute the remaining 225 g (2 cups) cheddar and 225 g (2 cups) mozzarella evenly over the casserole. Bake for 25 to 30 minutes, rotating the pan halfway through, until the cheese is deeply golden and bubbling.
06 -
Allow to cool slightly, cut into squares, and serve immediately while hot.