Season steak with salt and black pepper. Heat olive oil in a large skillet over medium-high heat. Sear steak for 3–4 minutes per side, or until desired doneness. Remove from pan and rest for 5 minutes, then slice against the grain.

Bring a large pot of salted water to a boil. Cook tortellini according to package instructions until tender. Reserve ½ cup of pasta water, then drain.

Reduce skillet heat to medium. Add butter and let it melt. Stir in minced garlic and cook for 30–45 seconds until fragrant (do not brown).

Stir in Italian seasoning, Parmesan cheese, and heavy cream if using. Add reserved pasta water a little at a time until the sauce reaches your desired consistency.

Add cooked tortellini to the skillet and toss to coat. Gently fold in sliced steak and optional add-ins like mushrooms or spinach.

Taste and adjust seasoning. Garnish with fresh parsley and red pepper flakes if desired. Serve warm.