To heat a nonstick pan or cast iron pan on medium heat. Bring a pot of water on the boil to make the pasta.
Heat butter and chicken until melted.
After butter has melted and the chicken is warmed, chop the chicken and add half the spinach to your pan.
Stir spinach every once in a while until it becomes wilted (1-2 min).
Stir in the remaining spinach until it is wilted (another 2-3 minutes).
After spinach has wilted, add heavy whip cream, salt, pesto, and bring to a boil.
Mix the pasta with the sauce once it is cooked. Toss the mixture well.
Garnish pasta with Parmesan Cheese. Red pepper flakes can be added if you like.
