Slice the mushrooms into even pieces - approximately 4/5mm thick
Mix together the chickpea flour and water to create a 'vegan egg'
Add in the finely chopped parsley, garlic and salt
Using a fork or tongs, dip each mushroom slice in the mixture
Coat the mushrooms in breadcrumbs or panko
Place the breaded mushrooms on a baking sheet sprayed with cooking oil. Then spray the tops with a small amount of oil too.
Bake for approx 8-10 mins on each side.
Making the vegan garlic aioli:
Add the aquafaba and salt into a blender & blend until combined.
Keep running the blender and very, very slowly drizzle the oil into the mix. You want to make sure it's fully combined as you go, so stop adding oil if you see it sitting on top of the mixture. Then start adding it again once everything is mixed.
Once the aioli has turned thick, and you've added in all the oil, you can add the lemon juice (if desired) and garlic.
Notes
Take care when adding the oil to the aquafaba mix. If you go too fast, you can't save it.