Step 1

You will need 6 loose-bottomed deep tart tins measuring 8cm across the base

Step 2

Cut the butter into small dice and rub into the flour with your fingertips until it has the texture of soft, fresh breadcrumbs. Alternatively, reduce to fine crumbs in a food processor

Step 3

Add the egg yolk, the pecorino and the water, a tablespoon at a time, stopping when you are able to bring the crumbs together into a rollable dough

Step 4

Wrap and chill the pastry in the fridge for 20 minutes

Step 5

Peel the butternut squash and scoop out and discard the seeds and fibres. Halve lengthways then slice into small pieces (about the thickness of a pound coin)

Step 6

Put the pieces of squash in a steamer basket and cook over boiling water for 7-10 minutes until tender. Remove, allow to cool and refrigerate

Step 7

Set the oven at 170C fan/gas mark 5

Step 8

While the pastry rests, brush the tart tins thoroughly with melted butter

Step 9

Divide the pastry into six, then roll out each piece to fit the tart tins

Step 10

Line the tins with the pastry, pressing it gently into the corners

Step 11

Fill each with greaseproof paper or foil and baking beans, rest for 20 minutes, then bake for 20 minutes

Step 12

Carefully remove the beans and paper and return the pastry cases to the oven for 5 minutes or until the pastry is biscuit coloured and dry to the touch

Step 13

Remove and set aside till the next morning. (Once the pastry is cool, you may like to loosen them from their tins.)

Step 14

The next morning, cut the pancetta into pieces the size of a postage stamp and fry in a shallow pan until crisp. Remove from heat

Step 15

Preheat the oven at 160C fan/gas mark 4

Step 16

Beat together the eggs, cream and milk, then season with black pepper and the chopped rosemary leaves

Step 17

Place the pastry cases in their tart tins on a baking sheet, then divide the slices of butternut and pancetta between them

Step 18

Pour in the custard, making sure none goes over the edges (it will stick the tarts to their tins) and dust the surface with the grated parmesan

Step 19

Bake for 25 minutes until the custard is just set

Step 20

Remove from the oven and leave for 15 minutes or so before gently easing the tarts from their tins