Stack the burgers! Cut the buns in half. Place one half of the buns onto the plates and top with lettuce, and tomato. Place the cheesy burger on top and add the crispy onions. Sandwich with the other half of burger bun. Serve with the charred corn.
Preheat the oven to 180°C. Place the burgers on a baking sheet and bake for 8 minutes.
Heat the oil in a large frying pan and cook the onions until caramelized (about 5-10 minutes over a low heat).
Place the corn on the cob in a pan of simmering water for 5-8 minutes.
Heat a griddle pan or frying pan to very hot, spray a little bit of oil onto the corn and char for a minute and turn frequently.
Remove the burgers from the oven and place a cheese slice on top of each burger. Return the burgers in the oven for 3-4 minutes, adding the buns to the oven for the final 2 minutes of the cooking time.