Make the pastry: rub the cold butter into the flour and salt until it resembles breadcrumbs. Add cold water 1 tbsp at a time until the dough just comes together. Wrap and refrigerate for 30 minutes.

Preheat oven to 190°C (375°F). Roll out the pastry and line a 23 cm tart tin. Blind bake with baking paper and weights for 15 minutes. Remove weights and bake for 5 minutes more.

Fry the lardons until golden. Drain on paper towels.

Whisk together the eggs, cream and milk. Season with salt, pepper and a grating of nutmeg.

Scatter the lardons and half the grated Gruyère over the pastry case. Pour in the egg mixture. Scatter the remaining cheese on top.

Bake for 25–30 minutes until the filling is just set with a slight wobble in the centre.

Cool for 10 minutes before slicing. Serve warm or at room temperature.