Bring a large pot of salted water to boil. Cook tortellini according to package directions until al dente. Reserve 1/2 cup pasta water, then drain and set aside.

Pat steak pieces dry with paper towels. Season with Cajun seasoning, smoked paprika, garlic powder, salt, and black pepper.

Heat olive oil in large skillet over medium-high heat. Sear steak bites for 2-3 minutes per side until browned. Remove and set aside to rest.

Reduce heat to medium. Melt butter in same skillet. Add garlic and cook until fragrant, about 1 minute. Stir in red pepper flakes, Dijon mustard, and lemon juice. Add parsley and chives.

Return cooked tortellini and steak bites to skillet. Toss until coated in cowboy butter sauce. Add reserved pasta water as needed. Stir in Parmesan until melted.

Plate while hot. Garnish with extra Parmesan, parsley, and Cajun seasoning. Serve immediately.