Start by bringing a large pot of water to a rapid boil. Season the water generously with salt. Add the pasta and cook according to package directions until al dente. Drain and reserve about ½ cup of pasta water.
In a large skillet, heat the olive oil over medium heat. Add the diced onion and sauté for about 2 minutes until translucent.
Add the minced garlic and cook for an additional minute until fragrant.
Stir in the shredded rotisserie chicken and pour in the chicken broth. Bring to a gentle simmer.
Lower the heat and incorporate the heavy cream, stirring until well combined. Season with garlic powder, Italian seasoning, salt, and pepper. Let simmer for 4-5 minutes to thicken the sauce.
Add the fresh baby spinach and halved cherry tomatoes, cooking for another 2-3 minutes until the spinach is wilted.
Gently fold the cooked pasta into the skillet, tossing everything together. If the sauce is too thick, add reserved pasta water gradually.
Stir in the grated Parmesan cheese until melted and creamy. Adjust seasoning to taste.
Serve hot, garnished with fresh basil leaves and extra Parmesan cheese if desired.
Notes
Reserve some pasta water to adjust the sauce consistency.