Bring a large pot of salted water to a boil and add the 12 oz linguine pasta. Cook according to package instructions until al dente, around 8-10 minutes. Reserve ½ cup of the pasta water, then drain and set aside.

Pat 1 lb of sirloin or ribeye steak dry and cut into bite-sized pieces. Season with salt, black pepper, and 1 tsp smoked paprika. Heat 2 tbsp of olive oil in a large skillet over medium-high heat and sear the steak bites for 1-2 minutes on each side until browned, then transfer to a plate.

In the same skillet, reduce the heat to medium and melt 4 tbsp of unsalted butter. Add 4 cloves of minced garlic and sauté for 1-2 minutes until fragrant.

Stir in 1 tsp of Dijon mustard and 1 tbsp of fresh lemon juice into the garlic butter mixture. Gradually pour in 1 cup of heavy cream and ½ cup of beef broth, mixing well, and let the sauce simmer for 2-3 minutes until slightly thickened. Whisk in ¾ cup of grated Parmesan cheese until smooth.

Add the cooked linguine, seared steak, and 2 cups of fresh spinach to the skillet, tossing gently until well coated and the spinach is wilted, about 1-2 minutes.

If the sauce is too thick, stir in a bit of reserved pasta water. Taste and adjust seasoning as needed. Serve warm, garnished with parsley and additional Parmesan.