Cook the pasta: In a large pot of salted boiling water, cook the spaghetti until al dente, according to package instructions. Drain and set aside.
Prepare the sauce: in a large skillet, heat 1 tbsp of sun-dried tomato oil over medium heat. Sauté the sliced onion and sun-dried tomatoes for about 2 minutes.
Stir in minced garlic, Italian seasoning, and red pepper flakes. Cook for an additional 30 seconds.
Deglaze the pan with white wine, then add chicken broth. Cook until the liquid reduces by half, about 4 minutes.
Finish the sauce: Reduce the heat to medium-low. Pour in the heavy cream and grated Parmesan cheese, cooking until the cheese melts, about 2 minutes. Add salt and pepper, if needed.
Combine: Stir in the spinach until wilted, then add the cooked spaghetti. Toss until fully coated in the sauce. Serve immediately with additional Parmesan on top.