Lemon Meringue Tartlets

Why This Lemon Meringue Tartlets Works

During baking, the tart shells stay tender and crisp because the cold butter melts into the flour and sugar, leaving tiny pockets in the dough. As the shells heat, the egg yolk sets and holds everything together, so the crust doesn’t crumble when the filling goes in.

On the stove, sugar and cornstarch in the lemon mixture swell and thicken as the water and lemon juice heat up. After a few minutes, the cornstarch has soaked up enough liquid that the curd becomes smooth and thick instead of runny. When the egg yolks go in, gentle heat cooks them so they firm up and give the lemon layer a creamy, sliceable texture that stays in place inside the tart shells.

In the mixer bowl, egg whites and cream of tartar trap air as they’re beaten. Gradually adding superfine sugar makes the foam stable, so it holds stiff peaks. In the oven, that meringue sets on top while the sugar inside keeps it soft and marshmallow-like underneath, giving a light, fluffy cap that doesn’t collapse over the warm lemon curd.

Mistakes To Avoid

Letting the tart shells bake too long turns them from crisp to hard and dry. The edges darken quickly, and once cooled they become tough, so biting into the tartlet feels more like a cookie than a delicate shell.

Adding the egg yolks to the lemon mixture while it is boiling hot can scramble them. Little yellow bits form instead of a smooth curd, and the filling ends up grainy and lumpy instead of silky.

Pouring hot lemon curd straight into very hot shells and topping with meringue right away can cause the filling to stay too loose. The heat trapped under the meringue makes the curd slide around, so when the tartlets are cut or bitten, the filling oozes out.

Beating the meringue only to soft peaks and stopping early leaves it too loose and foamy. In the oven it can collapse, weep liquid, and slide off the lemon layer instead of holding a tall, fluffy shape.