You can decrease the amount of butter and flour here to 2 Tbsp. each if you want to lighten this recipe up even more, but you’ll need to cook the sauce longer so it still has a chance to thicken properly.
Reserve 1/2 cup of pasta water before you drain the pasta – if your sauce is too thick when you go to stir in the pasta, you can thin it out by adding some of the pasta water to the sauce.
Sauce too thin? Let it cook for several minutes more to thicken up. Too thick? Thin it out by stirring in a splash of pasta water or milk.
Substitute shrimp, salmon, or sausage for the chicken, or leave out the protein to make this vegetarian.
Use arugula or kale in place of spinach if you like.
Add your favorite veggies to this sauce to make it a little heartier! I like to add peas, broccoli, arugula, tomatoes, bell peppers, or even extra spinach.
For best results (and easy cleanup!) cook this sauce in a sturdy, nonstick pot (I love this one from Anolon!).