Bring a large pot of salted water to a rolling boil, then add the cheese tortellini and cook until just tender, about 3 to 5 minutes. Drain well and set aside.
Heat the olive oil in a large skillet over medium-high heat. Season the steak with salt, black pepper, garlic powder, and smoked paprika, then cook in the skillet until browned on each side, roughly 3 to 5 minutes. Remove the steak from the pan and keep warm.
Reduce the heat to medium and melt the butter in the same skillet. Stir in the minced garlic and cook until fragrant, about 1 minute.
Pour in the heavy cream and whole milk, stirring the mixture together. Let it gently simmer until it thickens slightly, around 3 to 4 minutes.
Slowly whisk in the parmesan cheese until it melts completely and the sauce becomes smooth and creamy. Taste and adjust seasoning if needed.
Return the seared steak pieces and cooked tortellini to the skillet and toss everything to coat evenly with the sauce. Cook together for an additional 2 minutes to blend the flavors.
Sprinkle with chopped parsley, cracked black pepper, and red pepper flakes if you like a bit of heat. Serve the dish immediately while warm.