Pre-heat oven to 110 fan forced.
Layer onion and garlic on the base of a foil tray and place brisket on top. Pour beef stock and Worcestershire sauce onto the brisket. Place a sheet of baking paper and then foil on top tightly.
Bake for two hours and then turn brisket around and cover again for additional 1 1/2 hours.
Pour liquid into a pan and cover the brisket again to rest for another hour. While brisket is resting put liquid on medium heat and reduce till the liquid is half the consistency. Slice brisket and place it in a brioche bun. Sprinkle cheese on top and place in the grill till the cheese has melted. Spoon some of the reduce liquid on top of the cheese and devour 👩🏽🍳