1) Preheat the oven to 450°F.
2) To make the filling: Melt the butter in a baking crock or Dutch oven over medium heat. Add the flour, and stir to combine.
3) Gradually pour in the stock, whisking constantly. Cook and stir the sauce over medium heat until it comes to a boil, then reduce the heat and simmer for 5 minutes.
4) Stir in the chicken and salt. Add ground black pepper and additional salt to taste. Set aside.
5) To make the biscuits: Combine the flour, sugar, and herbs.
6) Work in the butter until crumbly.
7) Whisk together the egg and milk, then stir into the dry ingredients, mixing until evenly moistened. The dough will be very wet and sticky.
8) To assemble: Drop the batter in golf ball-sized rounds into the pot with the chicken, spacing them evenly and leaving a bit of room in between for expansion. Place the pot in the oven (without the lid), and bake for 15 to 18 minutes, or until the biscuits are golden brown.
9) Remove from the oven and serve hot.
Yield: 8 to 10 servings.