Pat the shrimp dry with paper towels, then season evenly with salt and black pepper.
Heat a large skillet over medium heat. Add 2 tablespoons of butter and allow it to melt.
Add the shrimp in a single layer. Cook for 2–3 minutes on each side, flipping once, until pink, opaque, and cooked through. Transfer the shrimp to a plate and loosely cover with foil.
Add the remaining tablespoon of butter to the same skillet. Once melted, add the minced garlic and cook for about 1 minute, stirring frequently until fragrant.
Pour in the heavy cream and gently scrape the bottom of the skillet to incorporate the flavorful browned bits.
Stir in the chopped sun-dried tomatoes and simmer for 2–3 minutes over medium-low heat.
Add the spinach and stir until it softens and wilts into the creamy sauce.
Add Parmesan, salt, black pepper, Italian seasoning, and optional red pepper flakes. Stir gently until the Parmesan melts and the sauce becomes smooth and creamy.
Return the cooked shrimp to the skillet. Simmer the Tuscan Shrimp for about 1 minute, just long enough to warm the shrimp and coat them thoroughly in the sauce.
Sprinkle with roughly chopped fresh basil and serve immediately.