Cook pasta in salted water according to package directions. Save 1/2 cup of the cooking liquid and drain.
While the pasta is cooking, make the sauce.Heat the butter and olive oil over medium heat in a large skillet.Add shrimp, garlic and green onion and cook until shrimp turn pink. Remove shrimp with a slotted spoon and set aside. It's ok if you leave some of the green onion and garlic in the skillet. You should still have a fair amount of butter and oil in the skillet. If not, add a little more butter.
Place the skillet back over medium heat and add the flour. Cook and stir for 1 minute.Gradually whisk in the milk and bring to a simmer for 2 minutes.
Add the cream cheese, seasoned salt, and pepper and stir until the cream cheese is melted.
Reduce heat to low and stir in mozzarella cheese and Parmesan cheese.Return the shrimp and garlic mixture to the skillet.
Add the fettuccine to the skillet and mix it into the sauce. If the sauce is too thick, add some of the reserved pasta liquid.If your skillet isn't big enough, mix everything in a large bowl.
Add 1/2 teaspoon of crushed red pepper flakes if you want this dish spicy.