1) Pre-heat the oven to 180C/ 350 F/ Gas mark 4.
2) Toss the onion, beetroot, squash and garlic in 2 tablespoons olive oil and season with thyme, sumac and salt and pepper.
3) Roast for 45 minutes or until the vegetables are tender but still retain their shape, then stir in the lentils and half the chestnuts.
4) Squeeze the garlic from the skins, reserve half and squash the other two into the lentil mixture. Leave to cool completely.
5) Bring a large pan of salted water to the boil, tip in the kale, cook for 1 minute until wilted, then drain under cold water until cool. Squeeze all the water from the kale, then put it in the small bowl of the food processor along with the reserved garlic cloves, chestnuts, lemon juice, olive oil and salt and pepper.
6) Blitz to a thick paste like pesto and season to taste. Divide mixture into two.
7) On a lightly floured work surface unravel the two sheets of puff pastry.
8) Spread the kale pesto along the pastry base and then top with the cooked vegetables.
9) Brush all borders with some almond milk, fold over the ends, then carefully roll the pastry lengthways to completely encase the filling into a roll.
10) Place on a baking sheet lined with parchment paper.
11) Brush the top with the remaining almond milk, sprinkle with a little sumac and sesame seeds.
12) Bake for 30 - 35 minutes on 200C/ 400F / Gas mark 6 or until crisp and golden.