Saute all vegetables and garlic in butter 2 min on medium to medium-low heat. (Do not burn the garlic, as it will turn bitter.).
Turn heat to medium-low and add cream cheese. Stir until melted.
Add the heavy whipping cream a little at a time until incorporated into the cream cheese mixture.
Stir in remaining seasonings. (Start with smallest amount of cayenne and add more as it cooks, if desired).
Cover and simmer on low for 15 minutes, stirring every few minutes. (Sauce will thicken as it cooks.).
Uncover, add parsley, turn heat to medium to medium-low, and cook u too thickened, stirring frequently.
Add additional spice (garlic powder, cayenne, salt, pepper) as desired to taste.
Top fettuccine noodles with this sauce. You can also saute some chicken in garlic and butter, or shrimp in butter, garlic, and old bay seasoning, or broccoli and mushrooms in a little olive oil and garlic. This sauce can top any of these or fish! Have fun, be creative, and get cooking! .