Cook the pasta according to the package directions. Reserve ½ cup of the pasta water. Drain and set aside.
Melt the butter in a large skillet over medium heat. Add the garlic and cook for 1 minute. Add the flour and stir until mixed throughout.
Add the heavy cream and chicken broth. Bring to a gentle simmer and cook for 2-3 minutes.
Stir in the spinach, parmesan, and nutmeg. Cook until the spinach has shrunk and wilted.
Mix in the cooked pasta. If the sauce is too runny, let the pasta boil for a few minutes. If the sauce is too thick, add some of the reserved pasta water. Season to taste with salt and pepper and finish with fresh lemon juice.
Nutrition information is calculated using an ingredient database and should be considered an estimate.