01 - Preheat oven to 425°F. Line two baking sheets with parchment paper and lightly grease with cooking spray or olive oil.
02 - Separate onion slices into rings, reserving the smallest inner rings for another use.
03 - In three shallow bowls, place flour with spices (garlic powder, smoked paprika, salt, black pepper) in the first, whisk eggs and milk in the second, and panko breadcrumbs in the third.
04 - Dip each onion ring sequentially into the flour mixture, then egg wash, and finally coat thoroughly with panko breadcrumbs. Arrange the coated rings on prepared baking sheets.
05 - Lightly spray the onion rings with cooking spray or drizzle with olive oil to enhance crispiness.
06 - Bake for 20 to 25 minutes, flipping onion rings halfway through baking, until golden brown and crisp.
07 - In a bowl, combine mayonnaise, sour cream, buttermilk, chives, parsley, dill, garlic powder, onion powder, salt, pepper, and lemon juice. Stir until smooth and refrigerate until serving.
08 - Serve hot, crispy onion rings with ranch dressing on the side.