Heat the oven to 180C/fan 160/gas 4. Spread the nuts on a baking tray and roast them for 7–8 minutes until golden. Let them cool and then roughly chop them.
Remove the ends of the leek, wash and chop. Peel the pumpkin and cut it into 2cm cubes.
Melt the oil and 30g of butter in a large frying pan, add the pumpkin and fry on a high heat, stirring occasionally for 8–10 minutes until it starts to brown. Reduce the heat and add the spices, and cook for 1 minute. Then mix in the leek and cook for a few minutes before pouring 150ml of vegetable stock over it. Cover the pan and let it simmer gently until the stock has evaporated and the pumpkin has softened. Spread the mixture on a large plate to cool and then mix in the roasted nuts.
To assemble, melt the rest of the butter and brush a little on a baking tray. Layer 2 sheets of 'phyllo' at a time, brushing each with melted butter. Place a quarter of the pumpkin mixture along one of the long sides, leaving a 5cm border. Cut the cheese into cubes and place a quarter on each. Roll it all up and then twist the sides to create a cracker shape. Place on the baking tray, brush with more melted butter and scatter the sesame seeds on top. Repeat with the rest of the dough to make 4 crackers.
Preheat the oven to 200C/180C fan/gas 6 and bake for 30–35 minutes until crisp and golden. Serve immediately.
