Place the chicken, stock, and bay leaves into a medium-sized pot. Bring to a boil, cover, and simmer over medium-low heat for 1 hour. Remove chicken from the pot and let cool to the touch.
Strain cooking liquid, discard any strained bits, and set aside. Remove skin and bones from chicken and dice into medium-sized chunks, set aside.
Preheat oven to 375 degrees. Melt the butter in the same pot over medium-low heat. Add the onion, carrot, celery, garlic, and thyme. Stir to coat in the butter, cover, and cook, stirring occasionally, for 10 minutes.
Add the flour to the pan and stir to combine. Increase the heat to medium and slowly add in the milk, 1/2 cup of the reserved chicken cooking liquid, and the salt and pepper. Stir and let bubble until thickened, about 2-3 minutes. Add the diced chicken back to the pan with the peas. Coat everything in the sauce.
Divide filling equally between two 4x2 inch oven-safe dishes. Set aside.
For the Crust
Place all the ingredients in a medium-sized bowl. Roll everything between your fingers until the mixture is crumbly yet combined. This will take a few minutes.
Turn dough out onto a flour work surface, press dough into a ball. Divide into two pieces. Roll out each piece with a rolling pin a little larger than 4 inches in diameter and about 1/4 inch thick. Drape each piece over each baking dish, using a knife cut off any excess. Make a small hole in the top of the crust so the steam can escape.
Bake for 30-35 minutes, until the crust is golden brown.
Notes
To make a larger, family-style chicken pot pie double the ingredients in the filling, pour into a 9x2 inch baking dish. The crust recipe will be the same, except just roll out the whole dough into a large circle, 1/4 inch thick. Cover the entire pie with the crust and cut off any excess. Make a hole in the middle for the steam to escape. Bake per directions, if the crust is not browned to your liking, cook longer.
This can be frozen, see my storage tips above
You can make this into a larger pie, also see above on how to do that.
You can use any vegetables that you like!
You can use two chicken thighs if you do not have chicken breasts