Pat the shrimp dry. Moisture is the enemy of a good sear. Blot with paper towels and season with salt, pepper, and paprika.
Heat the skillet. Add 1 tablespoon olive oil and the butter over medium-high heat.
When the butter foams, add the shrimp in a single layer.
Sear the shrimp. Cook 1–2 minutes per side until just pink and opaque. Do not overcook. Transfer to a plate and tent loosely with foil.
Sauté the aromatics. Lower to medium heat.
Add the remaining 1 tablespoon olive oil. Stir in the shallot and cook 1–2 minutes until softened. Add the garlic and red pepper flakes; cook 30 seconds until fragrant.
Deglaze the pan. Pour in the white wine (or broth).
Scrape up any browned bits. Simmer 2–3 minutes to reduce by about half.
Build the sauce. Stir in the cream, Italian seasoning, and lemon zest. Bring to a gentle simmer.
Whisk in Parmesan until smooth. Taste and season with salt and pepper.
Add the greens. Fold in the spinach by handfuls. Let it wilt, stirring occasionally, 1–2 minutes.
If the sauce thickens too much, splash in a bit more broth or water.
Finish with shrimp and lemon. Return the shrimp and their juices to the skillet. Toss to coat and warm through, about 1 minute. Stir in the lemon juice.
Adjust seasoning.
Serve. Top with parsley and extra Parmesan. Serve over rice, pasta, mashed potatoes, or with crusty bread.