In cast iron skillet heat oil and melt butter medium heat. Add onion, celery, carrots and thyme and cook until veggies are soft.
Add garlic and cook about 2 minutes. Season with salt and pepper. Blend in flour and cook another minute.
Whisk in chicken broth and heavy cream stirring constantly until thickened.
Stir in chicken, bring to a boil then simmer for 5 minutes.
Remove from heat. Add peas and parsley and mix well. Top with biscuits and cook in oven at 400 for about 20 minutes.