Apple Custard Tartelettes Questions

Which apples work best if I can't find Boskoop?

Any firm, tart baking apple will do - Braeburn, Granny Smith or Elstar all hold their shape the same way Boskoop does. Avoid soft, mealy varieties, because the filling is sautéed briefly in a pan and a soft apple will collapse into mush instead of staying in distinct dice. The lemon juice and cinnamon in the filling are there to balance sweetness, so with a very sweet apple you may want to keep the sugar at the lower end.

Can I make the components ahead of time?

Yes, and it actually makes baking day easier. The pastry cream needs to cool completely anyway, so make it a day ahead, keep the plastic wrap pressed directly on the surface, and refrigerate it. The shortcrust dough also benefits from resting - the recipe calls for at least 30 minutes chilling, but a night in the fridge is fine; just let it sit at room temperature for a few minutes before rolling so it doesn't crack.

My pastry cream turned out lumpy - what went wrong?

Lumps almost always come from adding the hot milk too fast, which scrambles the egg yolk before the cornstarch can thicken it. Pour the hot milk into the yolk-sugar-cornstarch mixture in a thin stream while whisking constantly, then return it to the pot and keep whisking as it thickens. If it does go lumpy, push it through a fine sieve while still warm - it usually rescues the texture completely.

Why does the apple filling need to be drained, and what if I skip it?

The apples release juice as they cook with the sugar and lemon, and that liquid is what turns a crisp shortcrust base soggy. Draining well and letting the apples cool before they meet the pastry keeps the shells crisp. The cornstarch tossed with the apples binds some of the moisture, but it won't handle all of it on its own.

Can I substitute the yogurt in the shortcrust pastry?

Sour cream or crème fraîche works as a one-to-one swap for the 30 g of yogurt - you just need something with a similar moisture and fat content to bring the dough together. Cold milk works in a pinch but makes a slightly firmer dough. Whatever you use, keep it cold and knead only until the dough comes together smoothly, since overworking develops gluten and makes the baked shells tough rather than short and crumbly.