Oven Baked Onion Rings; Crispy onion rings, baking into the oven – not fried! 1 large white or yellow onion, peeled, sliced & separated into rings. 2 egg whites. 2 tbs milk. 1/2 tsp garlic powder. 1/4 tsp cayenne pepper. 2 c bread crumbs. 1/3 c flour. salt + pepper to taste. cooking spray. 1/3 c mayo. 1/4 c ketchup. 1 tsp hot Chili sauce (such as Sriracha).