Bring a large pot of salted water to a boil and cook pasta according to package directions. Drain and set aside.
Melt butter in the same pot. Add onion and garlic and cook until tender. Stir in flour.
Add sundried tomatoes (no need to drain, the oil they're packed in adds great flavor), milk, parmesan cheese, salt, and pepper. Bring to a simmer and cook until thickened.
Add spinach and cook until wilted. Stir in chicken if using.
Return pasta to pot and stir to coat. Enjoy!
Recipe by For the Love of Gourmet at https://fortheloveofgourmet.com/creamy-sundried-tomato-spinach-pasta/