Squash, leek, chestnut and gruyere puff pastry rolls - DELIZABETH

Ingredients

• 400 gr. roasted butternut squash
• 2 leeks, finely sliced
• 1 red onion, finely chopped
• 2 cloves of garlic, finely chopped
• 3 sprigs of thyme
• 1 tsp. fennel seeds
• Pinch of chilli flakes
• 100 gr. roasted chestnuts, roughly chopped
• 2 tsp. mustard
• 200 gr. gruyere, grated
• Salt and pepper
• 250 gr. of puff pastry (preferably in a rolled shape)
• 1 egg
• Sesame seeds