Brown the ground turkey, onion, and mushrooms in a skillet, salt and pepper to taste. While you are browning the ground turkey, cook the rice in a rice cooker or on the stove top. I usually make 4 cups of uncooked rice and I adjust the rice in the recipe to get a good consistancy. When these steps are done, in a large bowl combine the meat and vegies with the four cups cooked rice, add the water chestnuts, soup, soy sauce, and cheese. mix it all together and load into to a medium sized hallowed out pumpkin. Bake at 400 degrees for 2-3 hours or until the pumpkin is tender.
Everything that is put in the pumpkin is already cooked, so you don't have to worry about it being cooked. Basically you are cooking the pumpkin and warming the ingredients inside.