Preheat the oven to 350 F. In a large bowl, combine all ingredients except for the Jiffy mix. Stir well until the ingredients are incorportated then stir in the Jiffy mix until it is just combined. The batter will be lumpy.
Grease a 9x9 square dish. Pour the batter into the baking dish and lightly tap on a solid surface to release any air bubbles.
Bake the casserole for 15-25 minutes (checking every 5 minutes after 5 minutes) until the center of the casserole is cooked through and the top is golden brown.
Let the casserole set 10 minutes prior to serving, to fully finish cooking. Enjoy!