Bring a large pot of salted water to boil. Cook tortellini according to package directions until al dente, then drain and set aside.

Pat steak cubes completely dry with paper towels. Season with smoked paprika, garlic powder, salt, and black pepper, tossing to coat evenly.

Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add steak bites in a single layer and sear undisturbed for 2 minutes until golden, then flip and cook 1-2 minutes more for medium-rare. Remove to a plate and let rest.

In the same skillet, add remaining 2 tablespoons butter over medium heat. Add minced garlic and cook 30 seconds until fragrant. Pour in chicken broth to deglaze, scraping up browned bits.

Reduce heat to medium-low. Stir in heavy cream, Dijon mustard, lemon juice, lemon zest, and red pepper flakes. Simmer 2-3 minutes until sauce thickens slightly.

Add cooked tortellini to the skillet and toss to coat. Return steak bites with resting juices. Fold gently until evenly coated. Finish with fresh parsley.

Serve immediately with grated Parmesan if desired.