Cook pasta according to package instructions. Bring a large pot of water to a boil then add dried pasta a cook until al dente.
Season both sides of the steak with salt and pepper.
Heat a large skillet over medium-high heat. Once the pan is hot add oil.
When oil is heated, cook the steak for 2-4 minutes on each side, until the center reaches your desired temperature. For a medium rare steak remove when the internal temperature is at 130-135°F so the carry-over heat will rise to 140°F-145°F. Once cooked to your desired doneness remove steak from pan and set aside.
Melt butter in a large fry pan over medium heat. Add minced garlic and cook until fragrant, 1-2 minutes.
Whisk in cornstarch (or flour if using) until fully dissolved. Stir in broth and milk, stirring frequently. Allow the sauce to thicken and start to boil.
Once sauce is boiling add in mozzarella and parmesan cheese. Stir until melted. Add salt and pepper to taste.
Add in the cooked pasta noodles.
Stir in the sun-dried tomatoes, green chile, and the spinach. Allow pasta to cook for 2-4 minutes, or until the spinach is wilted. You can turn the heat off and cover with a lid until the spinach is wilted.
Slice the steak and add to the pasta. Sprinkle with chopped parsley, red pepper flakes, and extra parmesan as a garnish.
