Begin by heating about 2 inches of vegetable oil in a deep pot or fryer to 350°F (175°C).
In a large bowl, whisk together the flour, garlic powder, onion powder, paprika, salt, and black pepper.
In another bowl, pour the buttermilk.
Dip each cauliflower floret into the buttermilk, allowing any excess to drip off, then coat it in the flour mixture. Shake off any excess flour.
After coating in flour, dip the floret back into the buttermilk, then roll it in the breadcrumbs mixed with Parmesan cheese if using.
Carefully place the coated florets into the hot oil, frying in batches to avoid overcrowding. Fry for about 4-5 minutes or until golden brown and crispy.
Use a slotted spoon to remove the cauliflower from the oil and place on a paper towel-lined plate to drain excess oil.
Serve hot with your favorite dipping sauce.