In a large skillet or Dutch oven, melt the butter over medium-high heat.
Add the chicken cubes and cook until browned on all sides, approximately 5 to 7 minutes.
Stir in the diced onion and garlic, sautéing for 2 to 3 minutes until softened and fragrant.
Add the dry pasta, chicken broth, heavy cream, thyme, salt, and pepper to the skillet.
Bring the liquid to a boil, then reduce the heat to medium-low, cover, and simmer for 10 to 12 minutes or until the pasta is al dente.
Stir in the frozen peas, carrots, and corn, and continue to cook uncovered for 3 to 5 minutes until the sauce thickens and vegetables are heated through.
Remove from heat and stir in the Parmesan cheese until smooth and well incorporated.