Bring a large pot of well-salted water to a boil. Cook pasta according to package directions until al dente. Before draining, scoop out about 1/4 cup of pasta water and set aside. Drain and set pasta aside.

Pat steak pieces dry with a paper towel. Season evenly with salt, black pepper, and smoked paprika.

Heat a large skillet over medium-high heat. Melt 1 tablespoon of butter. Add steak in a single layer without crowding. Sear for 3 to 4 minutes until a deep golden crust forms. Flip and cook another 2 to 3 minutes. Remove from skillet and let rest.

Reduce heat to medium. Add remaining butter to the same skillet. Once melted, add minced garlic and saute for 1 to 2 minutes until fragrant and lightly golden. Stir frequently and watch closely to avoid burning.

Add drained pasta to the skillet and toss to coat in the garlic butter. Add a splash of reserved pasta water if the sauce feels tight. Add rested steak, parsley, chives, and red pepper flakes. Toss until combined and heated through.

Taste and adjust salt and pepper as needed. Serve immediately topped with freshly grated Parmesan cheese.