Add the squash, oil, salt and pepper to a baking tray and toss to combine.
Roast for approx 35 - 40 minutes or until soft
To cook the caramelised onions
Add the oil and sliced onion to a small pan and fry slowly on a low heat for 15-20 minutes until caramelised.
Then add the salt and pepper. Set aside.
To make the tart
Make the flax egg by mixing the ground flax and water in a bowl - set aside to thicken.
Add all the dry ingredients to a large bowl and mix to combine. Then add in the oil, almond milk and flax egg. Mix throughly to form a dough. Set aside
To make the pesto
Add all the ingredients to a food processor or high-speed blender and blitz until you get a chunky paste.
To compile
Divide the dough into four, then roll each out into discs.
Transfer the dough discs onto the baking tray, then spoon the pesto onto each base ( just into the middle - leave at least an inch around the edge).
Add the caramelised onion and squash.
Pull up the sides around the filling and pinch the dough a little to secure.
Bake for 15 minutes on Gas Mark 4/180. Remove from the oven to cool a little.