Season the shrimp: Pat shrimp dry with paper towels.
Toss with salt, pepper, Italian seasoning, and red pepper flakes. This helps them sear instead of steam.
Quick sear: Heat 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 remaining 2 tablespoons butter.
Stir in garlic and shallot. Cook 1–2 minutes until fragrant, being careful not to brown the garlic.
Add sun-dried tomatoes: Stir in the sliced tomatoes and cook 1 minute. They’ll release flavor and lightly toast in the butter.
Deglaze: Pour in broth.
Scrape up any browned bits on the bottom of the pan for extra flavor. Simmer 2 minutes to reduce slightly.
Make it creamy: Lower heat to medium-low. Stir in heavy cream and Parmesan.
Simmer gently 2–3 minutes until the sauce thickens and turns silky. Avoid a hard boil to prevent splitting.
Add greens and brightness: Fold in spinach until just wilted. Stir in lemon zest and juice.
Taste and adjust salt and pepper as needed.
Finish with shrimp: Return the shrimp and any juices to the skillet. Toss to coat and warm through for 1 minute. If the sauce seems too thick, splash in a bit more broth or cream.
Serve: Garnish with fresh herbs and extra Parmesan.
Serve hot with pasta, rice, mashed potatoes, or crusty bread.