In a deep pot set over medium-high heat, cook 1 tablespoon of butter with the chicken, onion powder, garlic powder, paprika, salt/pepper. Cook for 5 minutes until the chicken is cooked through.
Toss with 3 tablespoons of the basil pesto. Scoop the chicken out of the pot and set aside.
Add the garlic, onions and 2 tablespoons of butter. Cook a few mins.
Add the pasta and water.
Cook, stirring often, until the pasta is al dente, about 8 minutes.
Add milk, cream, Caesar dressing, the rest of the pesto, and the parmesan. Mix until creamy.
Slide the chicken back in, add the spinach if using and lemon juice. Stir and serve.