Bring a large pot of generously salted water to a rolling boil. Add cheese tortellini and cook 3 to 5 minutes until tender. Drain and set aside, reserving 1/4 cup pasta water.

Cut steak into 1-inch cubes and pat dry. Season with 1 teaspoon salt, 1/2 teaspoon pepper, 1 teaspoon garlic powder, and 1 teaspoon smoked paprika. Heat olive oil in large skillet over medium-high heat until shimmering. Sear steak 3 to 5 minutes until golden-brown on all sides and internal temperature reaches 135°F. Remove to a plate.

Reduce heat to medium and melt butter in the same skillet, scraping up browned bits. Add minced garlic and stir constantly for 1 minute until fragrant and golden but not brown.

Pour in heavy cream and whole milk, stirring to combine. Simmer 3 to 4 minutes until sauce reduces slightly and coats the back of a spoon.

Add parmesan cheese in three batches, stirring continuously after each addition until melted and smooth. Taste and adjust seasoning. Add reserved pasta water if sauce is too thick.

Return steak and tortellini to skillet. Toss gently for 2 minutes until everything is coated in sauce and heated through.

Remove from heat and serve immediately. Garnish with fresh parsley, cracked black pepper, and red pepper flakes if desired.