Preheat the oven to 180 °C/350F/gas4.

To prevent the filo drying out, cover it first with a sheet of greaseproof paper then with a tea towel wrung out in cold water.

Brush a 33x25cm baking dish with a little of the butter. Brush half the sheets of filo pastry with butter and lay in the baking dish, one on top of the other. Spread over the filling ingredients, then cover with the remaining pastry sheets, again buttering each one before laying it down. Using a sharp knife, tuck the edges down neatly round the sides. Brush with the remaining butter. Using a sharp knife, cut into diamonds. Bake in the oven for 25 minutes, then reduce the heat to 150 °C/300F/gas2 and bake for a further 30 minutes.

While the Baklava is cooking, put the sugar for the syrup into a pan with 300ml of water and the lemon juice. Stir over a medium heat until the sugar has dissolved. Bring to the boil and simmer for 5 minutes. Cool. As soon as the Baklava comes out of the oven, pour over the syrup, then leave to cool completely.