Season the shrimp: Pat the shrimp dry with paper towels. Season with salt, pepper, and half the Italian seasoning.
Sear the shrimp: Heat a large skillet over medium-high.
Add 1 tablespoon oil and 1 tablespoon butter. When hot and foamy, add shrimp in a single layer. Cook 1–2 minutes per side until just pink and opaque.
Transfer to a plate. Do not overcook.
Sauté aromatics: Reduce heat to medium. Add remaining oil and butter.
Stir in shallot and cook 1–2 minutes until soft. Add garlic and red pepper flakes and cook 30 seconds until fragrant.
Deglaze: Pour in chicken broth. Scrape up any browned bits from the pan.
Simmer 1–2 minutes to reduce slightly.
Make it creamy: Lower heat to medium-low. Stir in heavy cream and remaining Italian seasoning. Simmer gently 2–3 minutes until slightly thickened.
Avoid a hard boil.
Add cheese and spinach: Stir in parmesan until smooth. Add spinach in handfuls, stirring until wilted. Season with salt and pepper to taste.
Finish the dish: Return shrimp and any juices to the skillet.
Stir to coat and warm through, 1 minute. Add lemon juice and parsley. Taste and adjust seasoning.
Serve: Plate immediately.
Garnish with extra parmesan and lemon wedges. Great over zucchini noodles, spaghetti squash, cauliflower rice, or sautéed asparagus.