Measure out the Nuttelex or butter substitute of choice, and place in the freezer for 15-20 minutes. It needs to be cold to pull the galette together.
In your food processor, combine the flours, sugar, baking powder and salt. Pulse a couple of times to combine everything.
Mix together the psyllium husk, olive oil and water in a small bowl and set aside to solidify.
Add the 'butter' and psyllium husk mix to the processor, and pulse a few more times. The mixture should have visible chunks of butter substitute, but look a bit like slightly damp sand.
Turn the machine to a low-medium speed, and add the water, 1 tablespoon at a time, until the mixture just comes together. You should only need 1 tablespoon of water for this to happen. As soon as it goes, turn the machine off. Gather up the pastry, wrap in bees wax wrap or cling film, and pop in the fridge to firm up for at 20 minutes or so, climate dependent.