Place the chicken breasts in a pot with 1 quartered onion and 1 bay leaf. Fill the pan with just enough water to come to the top of the chicken breasts
. Bring the mixture to a low boil, reduce the heat to a simmer
the chicken 12 to 15 minutes. Remove the chicken and dice
with forks. Reserve the poaching liquid.
In the same pan, heat 2 tablespoons extra-virgin olive oil, a couple of turns of the pan over medium-high heat, add the mushrooms and lightly brown. When the mushrooms are just tender, add 2 chopped medium onions, potatoes, parsnips, celery, sage, salt, pepper and remaining bay leaf
. Cover the pot and sweat the vegetables 10 minutes, stirring occasionally. Remove the bay leaf. Melt
in the pot, add the flour and stir to make a light roux
the pan with a splash of white wine and add one to 2 cups of reserved poaching liquid. Whisk
in the mustard and 2 cups chicken stock. Stir in the cream. Thicken to a light gravy
consistency. Adjust the salt and pepper and add in the chicken.
Reduce the heat to low and bake off the pastry tops.
For make-ahead meal: Bake off the pastry tops; cool the filling and store. Reheat the filling, covered, over medium heat to a bubble, and then reduce the heat to a simmer.
To prepare the pastry tops: Cut the pastry into shapes which reflect the shape and size of the dishes or bowls you wish to serve the soup in. Beat the egg with a splash of water and arrange the cut pastry on a nonstick baking sheet or on parchment-lined sheet pan
. Brush the dough
with the egg wash
and bake to golden at 425 degrees F, 12 minutes.
Cook's Note: Chicken and Mushroom filling can also be served as a thick soup
with crusty, warm baguette