Slice the bun into two and butter each side. Set aside.
Put the avocado into a bowl, add a pinch of salt, pepper and use a fork to mash it into chunky pieces.
Grab a cheese slice, three chicken slices and rocket and set aside.
Add a splash of oil to a frying pan and heat on a low/medium heat. Crack the egg open into the pan and add a pinch of salt and pepper. Leave to cook for 3-7 minutes (depending on how runny you like your eggs) and do not flip it. Once the egg is ready place it on a paper towel to absorb all of the oil and set aside.
Put the base of the bun onto a flat plate. Add the ingredients in the following order: rocket, chicken slices, cheese slices, sunny side up egg, avocado and finally place the top half of the bun on top.
Notes
Add-ins: Feel free to add or omit any ingredients that you. For example, add leftover shredded chicken, mozzarella cheese and more.