Bring 8 cups water to a boil in a large pot, then add pasta and cook until al dente. In a large sauce pan, warm butter over medium heat.
Stir garlic into melted butter and let simmer until fragrant (about a minute or two).
Add flour, white pepper, milk, and heavy cream a little at a time and stir until smooth.
Once the sauce has started to bubble, turn the heat down to low.
Add Romano and parmesan and stir continuously until melted.
Once the sauce has thickened, add drained noodles to the sauce and stir together until fettuccine is thoroughly coated.
Add salt, pepper, and parsley and serve!