Prepare a double broiler, or fit a heat proof bowl over a large pot filled with an inch of simmering water.

In the heat proof bowl combine the lemon zest, lemon juice, egg, egg yolks, and sugar.

Cook, whisking CONTINUOUSLY (so you don’t wind up with sweetened scrambled eggs), until mixture thickens enough to cover the back of a spoon.

Remove bowl from heat, and add butter, stirring to combine.

Strain curd through a fine metal strainer to remove any (almost undetectable) pieces of cooked egg.

Cover with plastic wrap, so that it touches the top of the curd to keep it from developing a skin.

Refrigerate until chilled.

Preheat the oven to 250° F.

Mix together the corn starch and sugar in a small bowl and set aside.

Using a paper towel, wipe the bowl of a stand mixer with a tiny bit of vinegar to remove any fats or oils that could keep the egg whites from fluffing up.

In the bowl of the stand mixer, combine the egg whites, cream of tartar, and salt on medium-low speed until soft peaks form.

With the speed on medium-high, slowly pour in the sugar and corn starch mixture in a continuous stream.

Increasing the speed to high, add the vanilla extract, and whip until stiff, shiny peaks form.

Use a spatula to dollop the whipped meringue onto a parchment-lined baking sheet, making about 6-8 mounds. The meringues will not grow very much, so do not worry about putting them close to each other.

Reduce the oven to 225° F and bake for about an hour, or until the meringues are dry to the touch, but not browned or cracked.

Let cool on a cooling rack before serving.

With stand mixer or by hand, beat heavy whipping cream until it begins to froth, a couple of minutes.

Add the vanilla and powdered sugar, and continue beating until soft peaks form.

To assemble, spread a couple of tablespoons of chilled lemon curd over each cooled meringue, then top with a dollop of whipped cream and serve (optional: top with berries).