Heat a little oil in a small saucepan over medium heat, add the sliced onion and cook for 5 minutes until soft.
Reduce the heat to medium-low and continue to cook, stirring every few minutes. If the onions start to burn or stick to the bottom of the pan, reduce the heat to low. You can also add a splash of oil or water if the pan starts to dry out. Continue to cook until the onions are brown and sticky.
Add garlic powder, smoked paprika and chilli powder and cook for 1 minute.
Next add maple syrup, again stir around the pot covering onions evenly and allow the maple to get sticky and caramelized. Pour in cider vinegar and cook until reduced with no obvious liquid.
Finally, add beer and ketchup, bring to a medium boil (not an aggressive rapid boil). Cook down until most of the liquid has reduced and reaches a thick jam-like consistency. Make sure to regularly stir the onions to ensure they don’t stick to the bottom of the pan and burn.
When you have a thick sticky onion jam remove it from the heat and allow to cook for 10 minutes.
To finish stir through salt, pepper and whiskey. Transfer to an airtight sterilized jar and refrigerate overnight before use. This will allow the flavours to meld and produce a wonderful rich flavour.