Preheat your oven to 350°F (175°C).
Cook pasta according to package instructions until al dente; drain and set aside.
In a large skillet, melt butter over medium heat.
Add diced onions and celery; sauté until softened.
Stir in diced carrots and cook for an additional 5 minutes.
Add shredded chicken and mix well.
Pour in chicken broth and heavy cream; stir until combined.
Sprinkle in thyme and season with salt and pepper.
Fold in the cooked pasta and let simmer for 5 minutes.
Transfer to a baking dish and bake for 15 minutes until bubbly and golden.