Set up your Q for indirect cooking with the trivet and convection tray in place. Preheat on high for 10 minutes.
Brush the casserole dish with the melted butter.
Combine the milk, pastry mix, butter and eggs in a bowl (or food processor) and mix well using an electric beater. Pour this mixture into the casserole dish. Add the meat and place the onions, mushrooms, tomato, zucchini and cheese on top.
Once the Q is preheated, turn to the roast setting. Place the casserole dish on the trivet and cook for 50-60 minutes, or until the top is golden. When cooked, allow to cool before serving.