Bring a large pot of salted water to a boil and cook the rigatoni according to package directions until al dente; drain and set aside.
In a large skillet, melt the butter over medium-high heat.
Add the cubed chicken thighs to the skillet and cook until browned and fully cooked through.
Stir in the minced garlic and cook for about 1 minute until fragrant.
Add the sun-dried tomatoes and Italian seasoning, tossing to coat the chicken.
Pour in the heavy cream and bring to a gentle simmer, allowing the sauce to thicken slightly for 3-5 minutes.
Stir in the Parmesan cheese until melted and smooth.
Add the fresh baby spinach and stir until wilted.
Fold in the cooked pasta, tossing thoroughly to coat in the creamy sauce.
Season with salt and pepper to taste and serve immediately.