Combine chicken and broth in a large saucepan. Bring to a boil, cover and reduce heat to a simmer for 30 minutes.
Remove chicken, reserving the broth. Cut chicken into bite-size pieces. Set chicken aside. Add
Add cut-up vegetables to the reserved broth from the chicken. Bring to a boil, cover, and reduce heat to a simmer for about 15-20 minutes.
Stir in frozen mixed vegetables and set aside.
Melt 2 Tbsp butter in a medium to large saucepan at a medium to low heat. Stir in 2 Tbsp flour, mixing well.
Slowly add 1 cup milk or non-dairy type, stirring constantly cooking over medium heat. The mixture will begin to thicken and get bubbly. Remove from heat and add poultry seasoning and all other ingredients, including mushrooms. (Not biscuit ingredients) Gently mix well. Pour into a casserole dish.
To make biscuits combine flour, baking powder, and salt in a small mixing bowl.
Cut in butter or non-dairy substitute with a pastry blender until it is incorporated well and resembles a coarse meal.
Stir in buttermilk or non-dairy type. Spoon biscuit dough onto the chicken mixture in the casserole dish, making 6 biscuits. End with one in the middle.
Bake at 350 for 1 hour, biscuits will be a golden brown. Serve in shallow dishes.
*Note: This can also be cooked in separate oven-safe individual dishes. Which is helpful if someone is gluten-free and needs gluten-free biscuits. Reduce cooking time to 45 minutes.