Bring a large pot of salted water to a boil and cook the linguine according to package directions until al dente; drain and set aside.
In a large skillet over medium heat, warm the olive oil and 2 tablespoons of the butter until melted.
Add the minced garlic and red pepper flakes to the skillet and cook, stirring, until fragrant, about 30 seconds to 1 minute.
Add the shrimp, season with salt and black pepper to taste, and cook until the shrimp turn pink and opaque, about 2–3 minutes per side for large shrimp.
Stir in the Italian seasoning and add the baby spinach; cook until the spinach is wilted, about 1–2 minutes.
Return the drained pasta to the pot or transfer the shrimp mixture to the pasta. Add the remaining butter, grated Parmesan, and chopped parsley, then toss until the butter is melted and everything is well combined.
Stir in the lemon juice, taste and adjust seasoning if needed, then serve immediately.
