Place a frying pan/skillet over a medium heat and add the butter.
When the butter has melted, add the chopped red onion, tomato puree and chopped garlic to the pan and cook them for about 5 minutes, stirring frequently. The onion should be soft and sweet.
Add the sugar, stir in and remove from the heat.
Allow to cool for 10 minutes.
Transfer the mixture into a large mixing bowl and add the Worcestershire sauce with the hot sauce (optional) to the bowl and mix well.
Add the grill/bbq seasoning and the minced chicken to the bowl and combine everything fully.
Divide the mixture into 4 good size burger patties and put to one side in the fridge until needed.
Toast the bread and add to a blender to get coarse breadcrumbs. (I prefer this way than using panko etc). Pour breadcrumbs into a shallow dish.
Whisk the eggs in a shallow dish and carefully dunk the burger patties. Then place them into the breadcrumbs dish making sure they are fully coated.
When your ready to eat, add the olive oil to a pan over a medium high heat and add the patties.
Cook for about 6 minutes each side turning when the breadcrumbs are lovely and golden.
Whilst they are cooking, prepare the rolls. Slice in half and toast if you prefer.
Slice the pickles lengthways and put to one side with the remaining half of the red onion.
When cooked through, add the cheese slices to the burgers and cover with a lid for 30 seconds.
Remove the lid and place a pattie on the bottom part of a roll. Add the sliced onion and sliced gherkin and any sauce you want and top with other half of the bun. Repeat until they are all done.