Preparation

1. Bring a large pot of salted water to a boil. Add the tortellini and cook according to package directions until just tender. Reserve 3/4 cup of the pasta water before draining. Drain the pasta and set aside.
2. While the pasta cooks, pat the steak dry with paper towels. Season both sides generously with salt, black pepper, garlic powder, and a light dusting of smoked paprika. Let it sit a few minutes at room temperature.

Cooking

1. Heat a large skillet over medium-high heat until very hot. Add 2 tbsp olive oil. Lay the steak in the pan and sear without moving for 2 to 3 minutes, until a brown crust forms. Flip and sear the other side another 2 to 3 minutes for medium-rare (adjust time for thickness).
2. Transfer the steak to a cutting board and let it rest for 5 to 7 minutes. Slice thinly against the grain when ready.
3. Reduce the pan heat to medium. Add 4 tbsp butter to the skillet. When the butter melts, add the minced garlic and cook, stirring, until fragrant, about 30 seconds to 1 minute. Be careful not to burn it.
4. Pour in 1 cup heavy cream and 3/4 cup whole milk. Stir to combine and bring to a gentle simmer. Scrape the bottom of the pan to loosen browned bits.
5. Slowly stir in 1 1/4 cups parmesan until the cheese melts and the sauce becomes smooth. If the sauce feels too thick, add a splash of the reserved pasta water.
6. Add the drained tortellini to the pan and gently toss to coat. Fold in the sliced steak to warm through. Taste and adjust seasoning with salt, black pepper, and a pinch of red pepper flakes if using.
7. Finish with chopped parsley and a scatter of cracked black pepper. Serve right away.