Chop your butternut squash into cubes (no need to peel it), place into a baking dish and drizzle over olive oil, pinch of salt and pepper and roast for 30 minutes
Meanwhile roughly slice your red onion and fry in a pan over a medium heat with olive oil and a pinch of salt until it softens (roughly 5-6 minutes)
Now add your puff pastry to a large baking tray
With a knife, gently score a line all the way round (roughly 1 inch) from the edges. This gives you a guide with how much to fill the tart plus helps fold over the edges later
Now with a fork make pricks across the middle of the pastry
Add your onion, roasted squash, chopped courgette, fennel seeds, vegan cheese and sprinkled California walnuts
Fold over the pastry edges and lightly coat with olive oil