Pat shrimp dry. Season with half the salt, pepper, and red pepper flakes.
Heat olive oil and butter in a large skillet over medium-high heat.
Sear shrimp in a single layer until just pink, 1–2 minutes per side. Transfer to a plate.
Lower heat to medium. Sauté garlic and sun-dried tomatoes until fragrant, about 1 minute.
Pour in chicken broth. Scrape up browned bits and simmer to reduce slightly, 2 minutes.
Stir in cream, Italian seasoning, remaining salt, and Parmesan. Simmer until lightly thickened.
Fold in spinach to wilt. Return shrimp and juices. Add lemon juice and toss to coat.
Remove from heat. Sprinkle with fresh basil and serve immediately.