Combine paprika, garlic powder, onion powder, black pepper, and salt in a bowl. Pat beef strips dry and toss with the spice blend and soy sauce. Heat olive oil in a large skillet over medium-high heat until shimmering. Sear steak for 2-3 minutes per side until browned. Transfer to a plate and add 1 tbsp butter to the pan, then wipe out most drippings.

Bring a large pot of salted water to a boil. Add rotini and cook according to package directions, about 9-11 minutes. Drain about 1 minute before fully tender. Reserve 1 cup of pasta cooking water.

In the same skillet, melt 2 tbsp butter over medium heat. Add minced garlic and cook for 30 seconds. Sprinkle in paprika, chili flakes, and black pepper, stirring for 15-20 seconds. Pour in heavy cream slowly, stirring. Simmer for 1-2 minutes. Remove from heat and stir in cheddar cheese until melted. Adjust salt and thin with pasta water if needed.

Add drained rotini to the creamy sauce and stir until coated. Return the cooked steak and fold in gently. Divide into bowls and garnish with fresh parsley.