Cook tortellini according to package instructions, then drain and set aside.
Heat olive oil in a large skillet over medium-high heat and sear the steak slices until browned.
Remove steak and set aside, leaving any juices in the skillet.
Add garlic to the skillet and sauté for 1–2 minutes until fragrant.
Pour in heavy cream and simmer for 3–4 minutes, stirring occasionally.
Stir in Parmesan cheese, salt, pepper, and red pepper flakes.
Return steak and cooked tortellini to the skillet and toss to coat evenly in the sauce.
Cook for an additional 2–3 minutes until everything is heated through.
Garnish with chopped parsley and serve immediately.