To make the pastry, tip the flour, butter and parmesan into a food processor with the cayenne pepper and pulse until the mixture resembles breadcrumbs. Add 2 tbsp cold water and the nigella seeds, then bring everything together using your hands. Roll into a ball and use straight away or chill for up to two days. Can be frozen for up to one month.

Roll the pastry out on a lightly floured surface, about 5cm larger than a 23cm fluted metal tart tin. Use your rolling pin to lift it up, then drape over the tart case so there’s an overhang of pastry on the sides. Using a small ball of pastry scraps, push the pastry into the corners of the tin. Chill in the fridge for 30 mins, or, better still, in the freezer for 20 mins. Heat oven to 200C/180C fan/gas 6.

Lightly prick the base of the tart with a fork, line the tart case with a large circle of baking parchment or foil, then fill with baking beans or dried pulses. Bake the tart for 20 mins, remove the paper and beans, then continue to cook for 10 mins or until golden.

Heat a splash of oil in a shallow pan and add the pancetta. Cook over a low heat for 5 mins until golden. Use a slotted spoon to transfer the pancetta to a bowl, leaving the fat in the pan. Season the fat with ground black pepper, let that sizzle, then pour in the double cream, and stir. Bring to the boil, then turn off the heat and leave to cool. Stir the egg yolks and crème fraîche into the bacon-flavoured cream. Whisk the egg whites until light and fluffy and just holding their shape, then fold into the cream mixture with the spring onions.

Scatter the cheddar and pancetta over the base of the tart, then pour over the bacon cream. Top with the grated gruyère. Bake for 30 mins until set and golden. Leave to cool in the case, then trim the edges of the pastry. Remove and serve in slices.