Toast your hamburger buns with a tiny bit of butter. This gives you an incredibly delicious restaurant flavor and helps keep the toppings from soaking into the bun.  Start with the lowest time and work your way up. You do not want your burger to overcook.  Use 80/20 ground chuck for the best flavor.  No need to flip these burgers. The air fryer will prompt you midway, but you can ignore the alert and let it resume cooking.  Try making homemade buns! This recipe is particularly delicious served on my Onion Buns.