1. Preheat oven to 375. Rinse squash well, slice in half, scoop out seeds and place face down on a well oiled baking sheet. Bake until a knife can pass easily through any part of the squash, approximately 45 minutes. Set aside.
2. Place wild rice and 4 cups filtered water or stock in a large pot and bring to a boil. Cover, reduce heat to simmer and cook until rice kernels are open and just soft and chewy, approximately 50 minutes. Drain well.
3. While squash and rice are cooking, place oil in a large sauté pan on medium high heat. Add onion, celery and garlic and cook for 5 minutes, stirring frequently. Add remaining ingredients and cook for 5 minutes, stirring frequently. Add water or stock if necessary to prevent sticking. Place in a large bowl with drained wild rice and mix well. Stuff into squash and bake for 10 minutes.
Variation: Substitute roasted chestnuts for pecans. Add 1/2 cup corn and 1/2 cup sliced mushrooms.