Place 2 peppers on the grate of a gas stove, with the heat turned to high. Allow pepper to char on one side, then flip to opposite side using long metal tongs. Place in a bowl and cover with saran wrap. Repeat process with remaining two peppers. When pepper have cooled, remove the charred skin and discern the stem and seeds. (Do not rinse the peppers, you will lose all of their flavor)
Add the roasted red peppers, garlic, salt and black pepper to a food processor or blender and pulse until smooth. Remove and set aside.
Cook the fettuccine according to package directions. Drain, reserving 1 cup of pasta water and set aside.
To a large skillet with flat sides, add butter. When melted, add the cream cheese to the skillet. Use the back of a wooden spoon to break up the cream cheese.
When the cream cheese softens and begins to melt, add the milk and Parmesan cheese, and whisk to combine.
Add the roasted red pepper sauce to the skillet, and whisk to combine.
Add the cooked fettuccine to the skillet. Use tongs to toss the fettuccine and help coat it with the sauce and heat it through. Add pasta water a tablespoon at a time, as necessary to loosen the sauce
When well coated, serve in individual bowls and garnish with extra Parmesan cheese and fresh parsley.
*Vegan butter, cream cheese and nutritional yeast may be substituted for the regular butter, cream cheese, and parmesan. Unsweetened nut milk or vegetable stock may be used in place of the 2% milk