Season the steak: Pat the steak cubes dry and season with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper.

Cook the tortellini: Bring a large pot of salted water to a boil and cook the tortellini according to the package directions. Drain and set aside.

Sear the steak: Heat the olive oil in a large skillet over medium-high heat. Add the steak in a single layer, working in batches if needed, and sear for 2-3 minutes per side until browned but still pink in the center. Remove to a plate.

Build the sauce: Reduce the heat to medium and melt the butter in the same skillet, scraping up the browned bits from the bottom. Add the garlic and cook for 1 minute until fragrant.

Add the marinara and cream: Stir in the marinara sauce and heavy cream, along with the remaining 1/4 teaspoon salt and 1/4 teaspoon pepper. Bring to a gentle simmer and cook for 3-4 minutes until slightly thickened.

Finish with parmesan: Stir in the parmesan until melted and smooth.

Combine and serve: Return the steak and any juices to the skillet along with the drained tortellini. Toss gently to coat and cook for 1-2 minutes, just until the steak is warmed back through to at least 130-135°F for medium-rare. Top with fresh basil or parsley.