Ginger peach puffs

Ingredients

• 100g ginger nut biscuits (or speculoos), roughly crushed
• 60g unsalted butter, fridge-cold and cut into small cubes
• 1 lemon, ½ tsp grated zest, 2 tsp juice
• 1 tbsp fennel seeds, toasted and crushed
• ⅛ tsp fine sea salt
• 100g demerara sugar
• 3 ripe peaches (or nectarines), halved and stone removed (400g)
• 325g sheet of ready-rolled all-butter puff pastry
• 1 egg, beaten