If you plan to make your own tart crust, start with that first. Or, if you are using a boughten one, follow the package instructions to prepare it. Preheat your oven to 300° F / 150°C.

Cut open the vanilla bean pod lengthwise and scrape out the seeds. Discard the pod.

In a large bowl, stir together egg yolks and confectioner's sugar until it begins to lighten in colour.

Heat cream, milk, vanilla bean seeds, some freshly ground nutmeg, and strip of lemon zest in a medium saucepan over medium heat. As soon as it just comes to a boil, pour the hot cream mixture into the egg yolks, while stirring continuously.

Use a sieve to strain the custard into another bowl. Let it sit for a few minutes, then skim any froth from the surface and discard the froth.

Pour the custard into your tart crust, filling it just to an easy-to-move level, then top it up once it is safely set on the oven rack (to avoid messy oven spillage). Depending on your tart crust depth, you may not need all of the custard.

Bake the tart for about an hour, until the top is lightly golden and the custard is mostly set with just a slight jiggle in the middle when you tap the sides.

Set the tart on a cooling rack to cool completely before adding the grapes.

Cut the rounded edges off of each grape, then cut the remaining middle section into even slices. Depending on the size of your grapes, you will get 2-3 slices per grape.