Preheat your oven to 180 degrees celsius.
Scoop out the flesh of the feijoas into a medium sized bowl and mash roughly with a fork
Add, oil, egg, juice and zest of lemon, and vanilla to the mashed feijoa. Combine well with a whisk or fork.
In a second larger bowl, combine the dry ingredients: flour, baking powder, brown sugar and coconut. I do this with a whisk to ensure they are combined and any lumps of brown sugar or coconut are broken up.
Add the wet ingredients to the dry ingredients. gently combine with a wooden spoon or spatula to make the feijoa muffin batter.
Spoon the feijoa muffin batter into a 12 portion muffin tin. I line mine with a greaseproof bake cup.
optional extra: scoop the flesh from a couple of feijoas and slice thinly. Gently push into the top of the muffin and sprinkle with a little brown sugar.
Bake at 180 degrees for approximately 25 minutes