2Add shredded Le Gruyère to a nonstick baking sheet and top with onion slices.
3In a separate bowl, stir together breadcrumbs, seasoning and olive oil and stir to combine.
4Evenly distribute the panko mixture across the tops of the onions and place in the oven for 25 minutes.
5Meanwhile, in a bowl, mix together all the ingredients in the sauce and season with salt and pepper. Let it sit while the onions cook.
6Once the Le Gruyère is golden brown and Lacey around the edges, remove it from the heat and let it rest for 5 minutes before cutting it into bite sized pieces.