Fry bacon on stovetop until crisp enough to crumble.
Microwave peas in a bowl until mostly thawed.
Prepare Fettuccine noodles, drain water, return to pot.
Alfredo sauce
In medium saucepan over medium heat, place milk in first, adding other ingredients one at a time.
Using a rubber whisk (as to not scratch your saucepan), whisk your ingredients to blend together as they heat.
Bring to a boil, let reduce for a couple minutes, until it becomes well blended and gets thicker.
Putting it all together
Crumble half the bacon, put aside.
Pour sauce over prepared noodles, with heat on low-to-medium, mix together gently until sauce absorbs somewhat and thickens more.
Add peas and crumbled bacon, tossing gently but mixing together thoroughly, until heated through and combined.
If adding Mozzarella, add it now.
Serve with extra parmesan cheese shaken overtop
Notes
Turkey bacon is preferred here, as it's easier to get to a crisp and crumble. It's also healthier and less fatty than regular bacon.
You can make this healthier by using low-fat or skim milk, and low-fat cream cheese.