Preheat oven to 425.
Add the celery, onion, potatoes, and 2 tablespoons butter to a large oven safe skillet. Cook until the vegetables are getting tender, about 5 minutes.
Add one tablespoon of butter and 3 tablespoons of flour to the vegetables. Stir until the butter and flour are blended and it makes a paste.
Stir in the cream and the chicken broth.
Cook until the cream and chicken broth start to thicken. Add the chicken and the frozen mixed vegetables. Reduce heat and simmer while the biscuits are mixed together.
Add the flour, baking powder, and salt to a medium bowl and mix together. Add the shortening and cut in until coarse crumbs form. Add the milk and mix until the dough comes together.
Drop by heaping teaspoons the biscuits on top of the hot chicken filling. Place the skillet in the preheated oven and bake for 15 to 17 minutes. Serve.