1. Preheat your oven to 375°F (190°C) and grease a baking dish.
2. Cook the pasta according to package instructions until al dente, then drain and set aside.
3. In a large pan, heat oil over medium heat and cook diced chicken breast until golden and fully cooked.
4. Add minced garlic and diced onions to the pan and sauté until fragrant.
5. Stir in sun-dried tomatoes and fresh spinach, cooking until wilted.
6. Reduce heat and add cream cheese, heavy cream, and basil pesto, stirring until smooth and creamy.
7. Mix in grated parmesan cheese and season with salt and pepper to taste.
8. Add the cooked pasta to the sauce, stirring to coat evenly.
9. Transfer the creamy pesto chicken pasta mixture to the greased baking dish.
10. Sprinkle shredded mozzarella cheese evenly over the top.
11. Bake in the preheated oven for 20-25 minutes until bubbly and golden brown on top.
12. Let it rest for a few minutes before serving.
13. Garnish with fresh basil or extra parmesan cheese if desired.
14. Serve warm with a side salad or garlic bread.
15. Store leftovers in an airtight container in the refrigerator for up to 4 days.
16. Reheat in the oven or microwave before serving again.
17. Optionally, use rotisserie or leftover cooked chicken to save time.
18. For meal prep, assemble the dish ahead, refrigerate, or freeze before baking.
19. Enjoy your creamy pesto chicken pasta bake with friends and family!