Melt butter in a large skillet or Dutch oven over medium-high heat.
Add chicken cubes and sear until browned on all sides, approximately 5-7 minutes; remove chicken and set aside.
In the same pot, add onions, carrots, and celery; sauté until vegetables soften, approximately 5 minutes.
Stir in minced garlic and cook for 60 seconds until fragrant.
Sprinkle flour over the vegetables and stir constantly for 2 minutes to create a roux base.
Slowly incorporate chicken stock while stirring constantly to ensure a smooth texture.
Return the chicken to the pot and add thyme, salt, and pepper.
Simmer the mixture for 10-15 minutes until the sauce thickens and carrots are tender.
Stir in heavy cream and frozen peas, heating for an additional 2-3 minutes.
Garnish with fresh parsley and serve immediately.