For the cheeseburger, put the mince in a large bowl and season with salt and pepper. Use your hands to shape the mince into four burger-shaped patties. Wrap the patties in cling film and place in the fridge for an hour.
Heat a large frying pan and add the oil. Once hot, add the burgers and cook each side for 2-3 minutes. When cooked, set aside to rest.
In a small bowl, mix the mustard with the mayonnaise.
For the fries, preheat a deep-fat fryer to 180C/350F. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Fry the chips for 3-4 minutes, then drain on kitchen paper and season with salt.
For the vanilla milkshake, place all the ingredients in a blender and blend until smooth.
Just before serving, pour the milkshake into glasses.
To assemble the burger, place each patty in a brioche roll topped with the gherkins, sliced tomato, lettuce, a few onion slices, cheese and beer mustard mayonnaise.
Place the burgers on serving plates and secure with a wooden skewer. Place the fries alongside and serve with the milkshakes.