San Sebastian tartlets

Full-fat block cream cheese gives the thickest, most velvety result, so stick with it if you can. Spreadable tub varieties contain more water and can make the filling looser, so drain off any liquid before whisking. Whatever you use, whisk it smooth with the sugar and vanilla first, because lumps at that stage will still be there after baking.

That usually means the puff pastry was too warm and soft when you pressed it into the muffin tin. Roll and cut the log while the pastry is still cold, and chill the shaped shells in the tin for a few minutes if the dough starts to feel greasy. Also press the dough from the center outward all the way up the sides, so the walls are tall enough to hold the filling.

Yes - roll the pastry into a log, cut the 8 pieces, and press them into the muffin tin, then cover and refrigerate overnight. The filling can also be whisked ahead and kept covered in the fridge; stir it briefly before pouring, since the cornstarch settles. Fill and bake straight from the fridge, and just check the tartlets toward the end of the 18-22 minutes.

They are ready when the tops are slightly browned and the centers still wobble a little - the filling firms up as it cools. A slight dip in the middle is normal for this style of baked cheesecake, since it puffs up at 220 °C and settles again. Don't extend the bake to get a flat top, or the filling turns dry instead of creamy.

Let them cool in the tin first, then lift them out and keep them covered in the fridge; the filling contains egg and cream, so they shouldn't sit out at room temperature. They taste best on the day of baking, when the puff pastry is still crisp - after a night in the fridge the base softens a little. Take them out about 15 minutes before serving so the filling isn't fridge-cold.