Set up your barbecue for indirect cooking with a convection tray and trivet (refer to your handbook for further instructions).
Preheat your barbecue on HIGH for 10 minutes (refer to your handbook for further instructions).
In a bowl mix together the eggs, cream, onions, and Gruyère cheese. Grease a Weber Q Ware Frying Pan.
Place half of the pumpkin in a single layer in the base of the frying pan, then a layer using half of the baby spinach, followed by a layer using half the shredded ham. Pour 1 cup of the egg mixture evenly into the pan. Repeat the process with the remaining pumpkin, spinach, ham, and egg mixture.
Once the barbecue has preheated turn the control knob(s) to the roasting setting (refer to your handbook for further instructions).
Place the frittata onto the convection tray and trivet and cook for 25 minutes. After 25 minutes, sprinkle the top of the frittata with the Parmesan cheese. Continue cooking until the mixture is set and the Parmesan cheese is golden, 5 to 10 minutes more.