Pat the shrimp dry and season: Use paper towels to dry the shrimp well. Season with salt, pepper, and half the Italian seasoning. This helps them sear and stay juicy.
Sear the shrimp: Heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat.
Add shrimp in a single layer and cook 1–2 minutes per side, just until pink and opaque. Transfer to a plate. Do not overcook.
Sauté aromatics: Reduce heat to medium.
Add the remaining oil and butter. Stir in garlic and cook 30 seconds until fragrant. Add sun-dried tomatoes (and cherry tomatoes if using) and cook 1–2 minutes to soften.
Deglaze the pan: Pour in white wine or broth.
Scrape up any browned bits from the pan with a wooden spoon. Simmer 2–3 minutes to reduce slightly.
Build the sauce: Stir in heavy cream, remaining Italian seasoning, red pepper flakes, and a pinch of salt and pepper. Bring to a gentle simmer, not a rolling boil.
Add Parmesan: Lower the heat and sprinkle in Parmesan a little at a time, stirring until melted and smooth.
If the sauce seems too thick, add a splash of broth. If too thin, simmer another minute.
Wilt the greens: Add spinach and cook 1–2 minutes until just wilted and vibrant.
Finish the dish: Return shrimp and any juices to the pan. Add lemon juice.
Toss gently and warm through 1 minute. Taste and adjust salt, pepper, and lemon to brighten.
Serve: Garnish with chopped basil or parsley. Spoon over pasta, rice, or polenta, or serve with crusty bread.