Mix your vegan "egg": 1.5 tbsp ground linseeds and 4.5 tbsp water. Leave to rest in the fridge for 15min.
Peel the apple and cut it into small pieces. Squeeze the juice from the lemon slice all over the apple pieces.
In a separate bowl mix the almond flour and the baking powder together. I don't sift the flour so I use a fork to mix the baking powder in and break any lumps apart while I'm at it.
Mash the banana and mix it thoroughly with the softened butter. I use a handheld mixer.
Add the vegan "egg" and keep mixing until the mixture is well combined.
Add the flour and keep mixing.
Fold in the apple slices with a spatula.
Line a baking tray with baking paper and form six thick cookies with the dough.
Bake in a pre-heated oven (180ºC fan; 200ºC other oven types) for 25 minutes or until they are golden brown. Let them cool on the tray before you move them to a storage container!