1. Place chopped spinach in a large colander in the sink.

2. Bring a large saucepan of water to a boil over high heat. Add spaghetti and cook according to package directions.

3. Drain the pasta over the spinach to wilt it, then toss to combine.

4. Meanwhile, heat oil from the sun-dried tomato jar in a large skillet over medium heat.

5. Add sun-dried tomatoes and onion; cook, stirring, until softened, about 3 minutes.

6. Add garlic, crushed red pepper, salt, and ground pepper; cook for 1 minute.

7. Increase heat to medium-high and add broth. Cook, stirring, until reduced by about half, about 2 minutes.

8. Stir in sour cream, Parmesan cheese, and butter until smooth and creamy.

9. Add the spaghetti and spinach to the sauce; toss to coat thoroughly.

10. Serve immediately, garnished with extra Parmesan if desired.