Preheat oven to 410 degrees
In a large, deep mixing-bowl create buttermilk by combining plant milk and lemon juice - allow to sit for at least 5 minutes until it curdles
In a small bowl make a flax egg by combining ground flax and water - stir and allow to sit for 5 minutes, until it becomes gelatinous
In a large mixing bowl combine dry ingredients (garbanzo bean flour, ground mustard, smoked paprika, pepper, turmeric powder, garlic powder, onion powder, earth broth and salt) - mix thoroughly Pour the flax egg into the buttermilk, mix to combine
You should now have a dry ingredients bowl, wet ingredients bowl and your sliced mushrooms
Add half the sliced mushrooms into the wet bowl
Shake the bowl around and mix the mushrooms to coat thoroughly
Then, add your wet mushrooms into a lidded storage container or stasher bag*
Sprinkle with half of the dry flour batter, close lid and shake to coat all mushrooms in the spiced flour
Layer the floured mushrooms on lightly oiled parchment paper, spaced apart *
Repeat tossing the rest of your mushrooms in wet batter, dry batter and then layering them on oiled parchment paper
When all the mushrooms are placed, lightly spray them with olive oil *
Bake for 20-30 minutes (until they are golden and crispy), flipping them halfway
Serve warm straight out of the oven!