Preheat oven to 400 degrees F. Rub potatoes with oil and then wrap in tin foil. Poke a few holes through the foil and into the potato. Bake potatoes for at least one hour or until tender.
When potatoes are done cooking remove from oven and let stand while you make the chicken pot pie sauce.
Melt butter in a large, non-stick skillet over medium heat. Add carrots, celery, onion, garlic, salt and pepper. Cook and stir until vegetables are crisp-tender (not mushy!) for about 5 minutes.
Sprinkle flour over the vegetables and stir constantly for 1 minute. Slowly add chicken broth and whisk to combine everything. Continue to add broth and milk while whisking to make mixture smooth and to get rid of any flour lumps.
Continue to cook and whisk mixture until creamy and smooth. Add peas and cooked diced chicken. Let simmer on low heat for 5 to 8 minutes or until heated through. Season with salt and pepper.
Serve over warm baked potatoes and enjoy!