"This is a hearty main dish loaf that is an easy and tasty vegetarian substitute for turkey at Thanksgiving or Christmas, or on a cold winter night. My non-vegetarian family loves it at Thanksgiving served with mushroom gravy and a sugar pie pumpkin stuffed with dressing and baked."
Preheat oven to 400 degrees F (200 degrees C). Grease a 1-quart casserole dish with cooking spray.
Melt butter in a wok or very large skillet over medium heat. Add onion; cook and stir until translucent and soft, about 5 minutes. Reduce heat to low. Add Cheddar cheese, oats, pecans, cashews, eggs, milk, bread crumbs, salt, and white pepper; mix until completely blended.
Pack cheese-nut mixture into the prepared casserole dish.
Bake in the preheated oven until top is well browned and crispy, about 1 hour.