To make the filling, whisk together the cornflour and sugar in a saucepan, then gradually whisk in the milk. Add the vanilla and clotted cream, then set over a low-medium heat. Bring to a gentle simmer and cook, stirring regularly, for 6-8 mins or until it thickens to the texture of a thick crème pâtissière. Remove from the heat and set aside to cool, whisking occasionally to prevent lumps forming. Spread onto a plate and set aside to cool fully.

Heat the oven to 200C/180C fan/ gas 6. Line a large baking tray with baking parchment. Using a rolling pin, bash the frozen kunafah, still in its pack, until broken up into powdery pieces. Tip into a bowl and pour over the ghee, then toss together using your hands. Divide the mixture into two, tipping half onto a baking tray and patting out into a 24cm circle using your hands, ensuring there are no gaps. Using a spatula, scrape the cooled filling out on top of the kunafah, then scatter over the ricotta. Carefully cover with the remaining half of the kunafah mixture, trying not to leave any gaps. Bake for 30 mins until golden and crispy all over.

Meanwhile, to make the sugar syrup tip the sugar, lemon juice, vanilla and 250ml water into a saucepan and bring to a boil. Cook for 5-7 mins until the sugar has dissolved and has thickened slightly, then set aside to cool to room temperature.

Remove the kunafah from the oven and leave to cool for 15 mins, then invert onto a serving dish. Pour over the cooled syrup to serve and garnish with the pistachios, if using.