In a large pot, bring salted water to a boil. Add the fettuccine or linguine and cook according to the package instructions until al dente. Once cooked, drain the pasta in a colander and set aside.
In a skillet over medium heat, melt the butter and olive oil. Add the shrimp to the skillet and cook for about 2-3 minutes on each side, or until they turn pink and opaque. Remove the shrimp from the skillet and set aside.
In the same skillet, add the sliced green onions and minced garlic. Sauté for about 1-2 minutes, until fragrant, being careful not to burn the garlic.
Sprinkle the flour over the sautéed garlic and onions, stirring constantly for about 1 minute. Gradually whisk in the milk, ensuring there are no lumps. Continue to cook, stirring, until the mixture thickens slightly.
Stir in the cream cheese cubes, seasoned salt, and pepper. Mix until the cream cheese is fully melted and incorporated into the sauce.
Add the shredded mozzarella and grated Parmesan cheese to the sauce. Stir until the cheeses are melted and the sauce is creamy and smooth.
Return the cooked shrimp to the skillet, along with the drained pasta. Toss everything together until the pasta is well coated in the cheesy sauce. Serve immediately, garnishing with additional green onions or cheese if desired.
