Cook the Spaghetti: Bring a large pot of salted water to a boil. Add spaghetti and cook according to package instructions until al dente, around 8-10 minutes. Reserve some pasta water, drain, and keep warm.

Sauté the Garlic: In a skillet, melt 2 tablespoons butter. Add minced garlic and sauté for 1-2 minutes until fragrant.

Cook the Shrimp: Add thawed shrimp into the skillet. Cook for 5-7 minutes until pink and opaque.

Add the Tomatoes and Spinach: Stir in grape tomatoes and spinach. Cook for about 3-4 minutes until spinach wilts and tomatoes soften.

Combine with Spaghetti: Add reserved spaghetti to the skillet and toss, adding reserved pasta water until desired sauce consistency is achieved.

Season and Serve: Season with salt, pepper, and red pepper flakes. Toss and serve hot, optionally topped with grated cheese.