Melt 1 tablespoon of butter in a large heavy-bottomed skillet over medium-high heat.
Add cubed chicken and sear until browned and internal temperature reaches 165 degrees Fahrenheit; remove chicken from pan.
Melt remaining butter in the same skillet and add onion, carrots, and celery.
Sauté vegetables for 6 minutes until softened.
Add garlic and cook for 60 seconds.
Sprinkle flour over vegetables and stir constantly for 2 minutes to create a blonde roux.
Gradually whisk in chicken broth and heavy cream to ensure a smooth consistency.
Simmer for 5 minutes until the sauce has thickened to a nappe consistency.
Fold in the cooked chicken and frozen peas.
Season with thyme, salt, and pepper and heat through for 3 minutes before serving.