In a shallow dish, add 1/2 cup of the flour. In a separate shallow dish or mixing bowl, add the breadcrumbs. Set aside.
In a mixing bowl, add the remaining (1 cup) flour, baking powder and seasonings (garlic powder, onion powder, paprika, salt and pepper). Whisk to combine. Next, whisk in the buttermilk until a smooth batter forms. Mixture should have a thin pancake batter consistency. If batter is too thick, whisk in more buttermilk or water a little at a time to thin out.
In the bowl with the flour, coat the onion rings a couple at a time and transfer to a large baking sheet.
Next, coat the onion rings in the wet batter. Shake off excess batter and transfer to bowl with breadcrumbs. Coat both sides in breadcrumbs. Transfer to a large baking sheet arranging the breaded onion rings in a single layer. Repeat until all the onion rings are breaded.
Heat 1 1/2 to 2 inches of oil in a large cast iron skillet or heavy bottom pot to between 350F to 365F.
In batches, fry the onion rings for 2-3 minutes, flipping halfway through, until the onion rings are golden brown and crispy. Transfer fried onion rings to a wire rack set over a baking sheet to drain any excess oil. Repeat with remaining onion rings.
Sprinkle onion rings generously with salt to taste. Serve immediately with your favorite sauce. Enjoy!