Preheat oven to 400F. (THE OVEN MUST BE HOT FOR BEST RESULTS) Coat a large baking sheet with olive oil cooking spray. In a large bowl, combine flour, garlic powder, mustard powder and salt. Add onions and toss to coat. Pour buttermilk into a large bowl, add onions and toss to coat Place bread crumbs in a separate large bowl, add onions and toss to coat. Transfer onions to prepared baking sheet and spray with olive oil cooking spray. Bake until golden brown, 35 minutes. Serve hot. Yields about 1/2 an Onion per serving. This recipe yields 4 servings