Actually this is a recipe for the most amazing flourless gravy and it takes roasting a bird to make it. Try it with chicken, cornish hens, turkey, or capon. I'll use a turkey in the ingredients list and instructions since that's what I made.
Fill the cavity with carrots, celery, appple, orange and garlic; tie the legs with kitchen twine.
In a large roasting pan, spread the ingredients for "under the bird" in a stack about the same size as the turkey.
Place the turkey onto of the bed of vegetables and herbs.
Put butter on turkey.
Place the turkey in the oven and roast 45 minutes.
Pour half the chicken stock over the turkey; roast 45 more minutes.
Pour remaining stock over turkey and roast 45 more minutes. It will start getting golden brown.
Baste with pan juices, cover loosely with foil and roast an additional 45 minutes.
When the turkey has reached an internal temperature of 165 to 175 degrees, remove from oven, keep covered, and let rest at least 15 minutes before carving.
Strain the contents of the roasting pan into a bowl, keeping the solids in the strainer to use for the gravy. Remove the herbs and bay leaves.
Measure out 3 cups of pan juices and 1 cup of strained vegetables. Puree with a hand blender or in a standard blender. Add more vegetables until gravy is the desired thickness, or more juices if too thick.
Pour through a mesh striner again to make a smooth gravy.
Taste and season with salt and pepper.
Heat and serve with the sliced turkey.
I suggest that you make more than the 4 cups of gravy if you have enough juice and vegetables in your pan. It will be great on leftovers or to store in your freezer.