Peel and slice onions

Heat skillet on high heat, and once hot, add olive oil and butter.

When the butter is almost completely melted add onions and sauté until onions are coated with the oil and butter mixture, then lower heat to a simmer.

Add a pinch of salt to onions and continue to sauté so that the onions become uniformly soft and brown. Do not rush this process, the onions will take a little time to caramelize.

Add thyme, balsamic glaze and honey and combine.

If the onions begin to stick to the skillet add a little water and combine further making sure to incorporate the sticky remnants in the bottom of the skillet.

Allow onions to simmer until all ingredients are fully incorporated then remove from heat and set aside.

Place ground beef in a four separate bowls and separate out with a fork.

With a microplane, shred 1/2 tbsp of truffle butter over each portion of ground beef.

Using a fork gently combine as quickly as you can.

Form each portion of ground beef into a patty making sure the center of each patty is a little less dense than the outer edges. Just gently press down in the center with your fingers and thumbs while holding each patty in both hands. Do not overwork the patty.

Sprinkle burger patties with salt and cook to preferred temperature and then set aside, loosely covered with aluminum foil to rest for 3-5 minutes.

While burgers are resting grill brioche buns.

Build burgers by placing burger on top of base of bun, layer with two pieces of brie, and then top with lashings of caramelized onions.

Drizzle with balsamic glaze, and then finally place top of burger on top.

Serve immediately.