In a bowl, mix together the minced beef and egg with all the seasonings. Handle the mince with care as over mixing the mince can cause the meat to go tough.
Place the mince in a circular ring mould, there is enough mixture for 4 x 125g burger and place in the fridge for 20 minutes to set.
Meanwhile to make the burger sauce, mix the tomato ketchup, mayonnaise with the pickled gherkin and shallot which have both been diced finely.
Remove the burgers from the fridge. You can either cook the burger in a frying pan or under the grill both have a similar effect. Personally I prefer to cook them in a frying pan but it can be easier for timing if they are all cooked under a grill.
Slice the onion into strips and cook until they soften fully and caramelised.
While cooking the burgers, cook the bacon to a crispy-chewy texture.
If cooking the burger in the grill place the cheese on top and turn the grill off allowing the cheese to melt in the residual heat. If cooking in a frying pan place a lid over the top.
Slice the brioche buns in half and toast to prevent the burger sauce from making the bun wet.
Assemble the burger with sauce on the top and bottom with two cheeseburger patties, 2 rashes of smoked bacon, caramalised onions, sliced tomato and salad leaves.