Boil pasta shells until al dente. Drain and set aside.
Season steak bites with salt, pepper, and garlic powder. Heat olive oil in a skillet over medium-high. Sear the steak bites in batches, 2–3 minutes per side. Remove and set aside.
Lower heat medium. Add butter to the skillet, then garlic. Cook until fragrant, about 1 minute.
Stir in heavy cream, milk, Italian seasoning, and Parmesan. Simmer until thickened, about 3–5 minutes.
Add cooked pasta and steak bites to the sauce. Toss gently to coat.
Garnish with parsley and more Parmesan if desired.
