Chop carrots, celery, and yellow onion into small pieces and set aside in separate bowls.

Remove the leaves from the stems of the thyme and set aside.

Remove rotisserie chicken meat from the bones and set aside.

Preheat oven to 375 degrees.

In a large skillet pan on medium heat, add butter, onions, celery, fresh thyme, salt, white pepper, and garlic powder, and sauté until translucent. 

Next, add chicken broth, flour, milk, and Dijon mustard and stir quickly to achieve desired rue thickness and consistency. Note, you can add more or less broth or flour depending on your preference for thickness. 

Next, add carrots, chicken, and frozen peas mixing well to combine ingredients. 

Transfer the mixture to a 9 x 13 inch baking dish and bake for 30 minutes.

In a separate oven or rack, bake the biscuits as directed on the package or until golden brown and flaky. 

Once the pot pie mixture has baked, top with cooked biscuits or serve separately as you prefer. 

Enjoy!