Preheat oven to 200C/400F. Slice the head off of the garlic and squash slightly to try and open the cloves. Drizzle with a little olive oil and sprinkle with salt and pepper. Wrap in tin foil and place in the oven for 25-30 minutes, until lightly brown and cloves are soft if you squeeze slightly.
Whilst garlic is in the oven, chop the bacon into 1/2 inch pieces and place in a frying pan over a medium heat, cook until crisp.
When the bacon is almost ready, add in the diced onion and fry until translucent and browned.
Transfer to a plate covered in kitchen roll to drain. Leave to one side with the finished roasted garlic.
Scrape out the avocados and place in a medium sized bowl, season with salt and cayenne pepper and squeeze in lime juice. Mash with a fork until mostly smooth, some bigger lumps are fine.
Squeeze the garlic cloves out of their casings and chop roughly.
Stir in the drained bacon and onion, chopped garlic and then add in coriander if using.