Boil the fettuccine according to package instructions. As the water preheats, begin the sauce.
Melt the butter in a large saucepan over medium heat. Add the garlic and cook for one minute.
Whisk in the flour and cook for 1 minute, stirring continuously.
Add the heavy cream in splashes, stirring continuously. Add the milk in the same manner.
Bring to a gentle bubble, then reduce heat to a simmer. It will continue to thicken as it simmers.
Reduce heat to low and slowlystir in the cheese.Taste and season with salt/pepper if desired.
Drain the pasta and combine it with the sauce until well incorporated. The pasta will absorb the sauce and it will continue to thicken.
Garnish with parsley and serve!
Notes
Note: You may be tempted to add more cheese to thicken to sauce, but it continues to thicken upon standing and even when added to the pasta.For Saucier Pasta: Use 3/4 lb. pasta instead of a full pound.
Pro Tips for Reheating:
Alfredo sauce will thicken up and harden as it cools, but can be easily microwaved or slowly reheated on the stove top. Reheating in a makeshift double boiler is the best reheating method to restore it back to it's original form.
Frozen Alfredo sauce should be thawed overnight in the fridge before heating.
If the sauce is too thick when reheated, add a splash of milk or chicken broth to thin it out.