Cook the pasta: Bring a large pot of salted water to a boil. Cook linguine according to package instructions until al dente. Reserve 1/2 cup pasta water, then drain and set aside.

Sauté aromatics: In a large skillet, heat olive oil over medium heat. Add garlic and sun-dried tomatoes. Sauté for 1–2 minutes until fragrant.

Add spinach: Stir in spinach and cook until wilted (1–2 minutes for fresh; 3–4 for frozen).

Make the sauce: Reduce heat to low and pour in the heavy cream. Simmer for 2–3 minutes, stirring occasionally. Stir in Parmesan until melted and smooth. Season with red pepper flakes, salt, and pepper.

Combine pasta and sauce: Add the drained pasta to the skillet. Toss everything together, adding reserved pasta water a little at a time until the sauce reaches desired consistency.

Serve: Garnish with fresh basil or parsley and extra Parmesan if desired. Serve immediately.