Cook fettuccine pasta according to package instructions. Drain and set aside.
Heat olive oil in a large skillet over medium-high heat. Add the steak slices and sear for 2-3 minutes per side, until browned and cooked to desired doneness. Remove and set aside.
In the same skillet, melt butter and sauté garlic for about 30 seconds until fragrant.
Pour in heavy cream and milk, stirring well. Add Parmesan cheese, salt, black pepper, red pepper flakes, and Italian seasoning. Stir continuously until the sauce thickens, about 3-5 minutes.
Add cooked fettuccine to the sauce, tossing to coat evenly.
Slice the steak and place it on top of the pasta.
Garnish with fresh parsley and extra Parmesan before serving.