Heat butter in a large oven-safe sauté pan over medium-high heat. Cook until it begins to brown.

Add your pasta and stir to combine. Add garlic and cook pasta in brown butter for 3-5 minutes, until lightly golden brown and toasted.

Add flour to your pasta / butter mixture and stir to combine fully. Cook for another 2-3 minutes to remove the flour taste.

Pour in your vegetable stock and whole milk and stir to combine. Cook over medium-high heat for 8-12 minutes until your pasta is al dente.

When most of the liquid is evaporated and your pasta is mostly cooked, add kosher salt to taste, sour cream, and heavy cream. Turn heat down to medium.

Cook for 2-3 minutes until the mixture is creamy and bubbling. Then add 12 oz of your grated cheddar cheese and 6 oz of the grated parmesan.

Stir to combine into a thick, creamy, cheese mixture. Remove from heat and let stand for 5-10 minutes to chill.

Preheat oven to 400°F. Stir your Mac and cheese. Then, sprinkle the rest of the cheddar and parmesan cheeses on top evenly.

Cook Mac and cheese in oven for 10 minutes. Then, turn on the broiler and continue to cook until the cheese if fully caramelized and golden.

Let sit for 5-10 minutes before serving.