First, make the stuffing. Preheat the oven to 375F degrees. Place the four slices of bread on a baking sheet and bake them in oven for 10 minutes, flip over then bake another 6 minutes.
Remove from oven but leave the oven on. Cut the toasted bread into small pieces.
In a pan, on the stove over medium heat, melt the butter.
Add in the garlic, celery and onions and stir. Cook the veggies for 5 minutes, until softened. Add the chicken broth, parsley, sage, salt and pepper then stir. Bring the chicken broth veggie mixture to a boil. As soon as it is at a boil, add in the bread and stir quickly. Remove it from the stove and cover. Let the stuffing sit for 5 minutes then it fluff with a fork.
Cut the 10 small biscuits (or weighed out biscuit dough) into 6 pieces each. Spray a 9x13 casserole dish with nonstick cooking spray and spread the biscuit pieces on the bottom of the dish.
Because the topping is heavy, pre-bake the biscuits for 7-8 minutes (375F).
With the biscuits are cooking, mix together the turkey, stuffing, carrots, hash browns and the turkey gravy.
Spoon the mixture over top of the pre-baked biscuit pieces and make sure it’s spread evenly.
Cover with foil and bake the casserole in the oven for 35 minutes. Remove the foil and bake another 10-15 minutes - until the biscuits are baked through.
Divide the casserole into 6 equal servings.