Preheat oven to 350°F. Spray the bottom of a 13x9-inch baking dish with nonstick cooking spray.
Place the chicken, potatoes, and carrots into a Dutch oven pan. Then pour the broth over the top.
Place the pan over medium high heat and bring the broth to a gentle boil. Reduce the heat to medium, cover the pan, and simmer 18 minutes.
Add the asparagus and continue simmering for 2 minutes.
Remove the potatoes, carrots, and asparagus with a slotted spoon and drain well. Remove the chicken to a cutting board to cool slightly. Set aside 2 cups of the broth and throw away the remaining broth.
When the chicken has cooled, tear it into large shreds and place the shreds back in the pan. Return the vegetables to the pan and cover the pan.
Melt 6 tablespoons of the butter in a saucepan over medium heat.
Stir the onion into the butter and cook for 2 minutes.
Whisk the flour and seasoning salt in with the onions. Stirring continuously, cook for 1 minute or until the flour bubbles but isn't brown.
Slow stir in the 2 cups of reserved broth and bring to a boil. Stir and boil for 1 minute.
Reduce the heat to low and stir in the whipping cream. Cook the sauce, stirring continuously, for 5 minutes or until thick.
Pour the sauce over the chicken and vegetables, stirring to coat well. Make sure the chicken, veggies, and sauce are spread out evenly in the dish.
Sprinkle pot pie filling with mushrooms.
Separate the breadstick dough into 8 strips. Twist 3 of the dough strips and place them lengthwise over the filling.
Twist the remaining 5 strips of dough and place them crosswise over the top to form a lattice pattern.
Melt the remaining butter in a small bowl in the microwave. Brush the breadstick dough strips with the melted butter.
Bake pot pie for 35 minutes or until the mixture is bubbly around the edges. If the dough seems to be browning too quickly, cover the pan with foil to finish baking.