Method

1. Put the butter and flour in a food processor with 1/4 tsp salt and blend until the mixture resembles damp breadcrumbs. Or do this by rubbing the butter and flour together in a big bowl with your fingertips. Add the sugar and briefly whizz again or stir to combine.

2. Whisk the egg yolk with 2 tbsp cold water, and drizzle over the flour mixture. Use the pulse button to blend the mixture once more, keep going until it starts to form larger clumps. If the mixture seems too dry, add a little more water a tsp or 2 at a time, but no more than 3 tsp in total.

3. Tip out onto a work surface and briefly knead the dough to bring it together into a smooth ball. Avoid overworking or it will become tough. Flatten the dough into a puck shape and wrap well in cling film. Chill for at least 30 mins, or for up to 2 days, or freeze for 2 months.

4. Tip the plums, sugar and cornflour into a large pan, then toss to coat. Simmer for 3-5 mins, stirring now and then, until the plums have just begun to soften. Tip them into a sieve suspended over a large bowl, leave for 30 mins-1 hr, stirring every 10 mins, until the juice has all collected in the bowl.

5. Remove the dough from the fridge and divide into 2 pieces, one slightly larger than the other. Re-wrap the smaller piece of dough and set aside. Divide the larger piece of dough into the number of pies you’d like to make, or leave whole for a large one. On a lightly floured surface, roll out the dough to the thickness of a 50p piece, or until large enough to line the base of your pie plate or tin, with a little pastry overhanging. Roll the dough over your rolling pin, lift into the plate or tin and press it well into the corners. Scatter the almonds or polenta over the base.

6. Stir 2 tbsp of the strained plum juice and the almond extract into the plums. Spoon the filling into the pie dish, dotting the marzipan between the layers of plums as you go. Heat oven to 190C/170C fan/gas 5 and place a baking sheet on the middle shelf.

7. Top the pie with a lattice crust - follow the step-by-step images to see how to do this. First, arrange the pastry strips on top of your pie, with space between each one. Fold back alternate strips from the centre, then lay a strip across the middle, near the folds. Next, flip the folded strips back to cover the middle pastry strip. Fold back the strips that are woven under the middle piece. Finally, lay another strip across the middle, and flip alternate strips back again. Repeat until you have a woven pattern.

8. Once covered, whisk the reserved egg white and brush over the pastry. Scatter with a little extra sugar, then place on the baking sheet and bake for 45 mins for a large pie, 35-40 mins for medium pies or 25-30 mins for mini pies, until golden and bubbling. Cool for 10 mins before serving with cream or ice cream.