Sear the Steak**: Season the steak with salt, pepper, and smoked paprika. Heat olive oil in a skillet over medium-high heat. Sear the steak for 3-4 minutes per side for medium-rare or to your liking. Remove from the skillet and let it rest.
Cook the Shrimp**: In the same skillet, add the butter and shrimp. Sear until pink and cooked through, about 2 minutes per side. Remove from the skillet and set aside.
Sauté Onions and Garlic**: Add the diced onion and minced garlic to the skillet. Cook until softened, about 3-4 minutes.
Make the Sauce**: Pour in the broth, lemon juice, and zest. Stir in the heavy cream and Parmesan cheese, letting the sauce simmer and thicken for 2-3 minutes. Add the fresh spinach and allow it to wilt.
Combine and Serve**: Return the steak and shrimp to the skillet, tossing in the sauce to coat. Garnish with fresh parsley and extra Parmesan cheese. Serve hot and enjoy!