Prepare the Pasta and Spinach:

Boil a large pot of water. Cook the whole-wheat spaghetti according to package instructions for al dente texture.

Place the chopped baby spinach in a large colander. When the pasta is done, drain it over the spinach to wilt it naturally.

Make the Sauce:

In a large skillet, heat 1 tbsp of oil from the sun-dried tomatoes over medium heat.

Sauté the sliced onions and sun-dried tomatoes for about 3 minutes, until the onions are soft. Add minced garlic, red pepper flakes, salt, and black pepper. Cook for another minute, stirring frequently.

Pour in the broth and increase the heat to medium-high. Simmer and let the mixture reduce by half, about 2 minutes.

Combine Ingredients:

Reduce heat to low. Stir in sour cream, Parmesan cheese, and butter until the sauce is smooth and the cheese has melted.

Add the drained spaghetti and wilted spinach to the skillet. Toss everything together to coat the pasta and spinach evenly with the sauce.

Final Touches:

Adjust seasoning with additional salt or pepper, if needed.

Serve hot, garnished with extra Parmesan cheese if desired.