Peel onion, slice in half and slice as thin as possible. separate into individual half rings.
Add buttermilk and hot sauce to large bowl, add onion rings and soak at least 10 minutes and up to an hour
In another large bowl combine flour, parmesan cheese, sugar,salt, pepper, granulated garlic and chili powder, whisk well to combine.
Heat oil in dutch oven to 365. Fry onions by taking a handfull of rings out of the buttermilk, letting excess drip off and tossing with seasoned flour, again shaking off excess, add to hot oil and fry, using a fork to separate strands until golden and crisp, about 5 minutes. Drain on paper towels. Contiue cooking onions in batches until done.
Transfer to serving dish and sprinkle with extra parmesan cheese or salt. Serve hot.