Reserve ⅔ cup of gravy. Preheat your oven to 230° C (450° F), get out a shallow 8 or 9 inch round baking pan, like a layer cake pan.
In a saucepan on medium heat, add remaining gravy, mushrooms, pimento, olives, and season with pepper as desired. Stir to mix together.
Stir in the chicken, bring to a boil.
Pour mixture into the round baking pan.
Mix the sage into the biscuit mix, prepare dough according to package instructions but use the ⅔ cup gravy for the liquid called for in the instructions.
Roll dough out to the size of the baking pan and place on top of the hot mixture.
Bake for 15 minutes or until golden brown.
Run a knife around the edge. Place a deep plate, upside down on the baking pan, and carefully turn the baking pan and plate over and remove the pan.
Slice, serve, and enjoy.