Preheat your oven to 375 degrees F.
Cut the chicken into 1 inch chunks.
In a large deep frying pan, add about 1 tbsp olive oil and melt 1 tbsp butter. Then add the chicken to the pan and season generously with salt and pepper. Now brown the chicken, making sure not to over cook it...if the chicken is a little pink that's ok because it will continue to cook in the oven. Once the chicken is done, transfer it to a bowl and set aside.
In the same frying pan that was used to cook the chicken add more oil if needed, then add the onions, celery, carrots and potato. Sauté until soft, about 5 minutes.
Then add the thyme, bay leaf and flour and sauté for 1 minute, stirring continuously.
Now add the stock and bring the mixture to a boil, stirring constantly until the mixture thickens. This takes about 5 minutes.
Once the mixture has thickened, add the chicken.
Transfer the pot pie mixture into an oven proof casserole dish.
Bake covered for 1 hour.
After the 1 hour baking time, remove the bay leaf, then stir in the frozen vegetables and cream, and add the biscuit dough.
Adding the biscuit dough: I don't like to make this part fancy or fussy, so I just drop the biscuit mix into clumps spread out evenly on the top of the pie filling mixture. If you want, you can brush the tops with melted butter.
Bake the pie for about 30 minutes more, or until the biscuits are golden brown and the pot pie filling is bubbling.
Serve immediately!