In a bowl (or stand mixer) mix together the flour, sugar and a pinch of salt. Then mix in the butter, using your hands or the paddle of your stand mixer, until well incorporated. The resulting mixture will look a bit like little pebbles. Then the egg yolk (if using) and enough cold water so that the mixture just forms a solid dough. Do not knead or overmix, which will make the dough tough. And you should do this all quite quickly, so that the butter does not start to soften too much.

Wrap the dough in plastic wrap and put it in the fridge for 30 minutes or more, to let the dough rest and stiffen up again.

(NB: While the dough is resting, you can make the frangipane base and slice your apples.)

Take the dough out of the fridge, remove the plastic wrap, and roll it out with a rolling pin into a round that is at least an inch wider than the tart pan in which you intend to bake your crostata.

Using your rolling pin, roll up the dough and then unroll it over the tart pan, trying as best you can to center it well. Gently push the pastry into the bottom of the pan with your fingers. (If, as sometimes happens, your pastry doesn't quite reach the edge of the pan, you can always 'nudge' the pastry outwards to cover the edges of the pan.) Prick the pastry with a fork all over to prevent puffing while it bakes. Then trim off any excess pastry, using the edge of the tart pan as your guide. (NB: If you prefer, you can leave the excess on and fold them inward over the filling when the time comes.)

In a large bowl, cream together butter and sugar in a mixing bowl. Add the rest of the ingredients and mix them well until you have a smooth paste. You can use a wooden spoon to start and then, once the ingredients are mixed, switch to a whisk to smooth the mixture out. But you can do with in one go, in a fraction of the time and with little effort, using a KitchenAid or other stand mixer, with the whisk attachment.

When your pastry shell is ready, take the frangipane and slather it out evenly over the bottom of the shell with a rubber spatula. This will act as a 'bed' for your apples and help anchor them in place.

Peel, core and slice the apples into thin half-rounds. Then arrange them attractively in the tart pan. Push one side gently into the frangipane bed, then lay it on its side. Proceed with the next piece, slightly overlapping the proceeding one like roof tiles, continuing around in concentric circles until the entire shell is filled with a single layer of apples slices. Trim off any excess pastry—or, if you prefer, you can fold the edges over the outside of the apples.

Now you are ready to bake your tart: If you have one large enough, place the tart pan on a cookie sheet (this will catch any spillage from the tart, but is not 100% necessary.) Place the tart pan in the hot oven (200C, 400F) for about 15 minutes, then lower the temperature to a moderate oven (180C, 350F) and bake for another 10 minutes, then sprinkle the apples with ample sugar, and bake for another 10 minutes or more, or until the apples have nicely browned along their edges and are perfectly soft when pierced with a knife.

Remove the tart from the oven, place it on a cooling rack and let it cool off in its pan.

If you like, you can finish off the tart with an apricot glaze. To make the glaze, take apricot preserves and force them through a fine sieve with a wooden spoon or rubber spatula—this will smooth out the consistency, as preserves usually have little bits of fruit in them. Then take this purée and heat it gently in a small saucepan with a spoonful or two of sugar to taste, depending on how sweet the preserves are in the first place. Thin out the purée with some water, until you have reached a brushable consistency.

Once the tart has cooled, brush over the warm glaze evenly over the entire surface of the apples, but avoiding the pastry.

Now you're done! Enjoy your crostata di mele either by itself—it is perfectly delicious—or, if you want to gild the lily, with some whipped cream or vanilla ice cream.