Cream together butter and confectioner’s sugar until light and fluffy. Add in egg and mix well. Incorporate almond meal and plain flour until just combined. Chill the dough for 1 hour.

Preheat the oven to 160°C (325°F). Roll out the pastry dough and press it into the tart pan. Bake for 20-30 minutes until golden. Remove from oven and cool.

Heat milk and vanilla in a saucepan until steaming. In a bowl, whisk egg yolks, sugar, and cornstarch together. Gradually combine with warm milk, then cook over low heat until thickened.

Simmer rhubarb with sugar and a splash of water until tender. Mash some for a smoother compote or keep whole for texture. Cool before using.

Pour the custard into the cooled tart shell, then top with rhubarb compote. Chill for at least 30 minutes to set before slicing.

Slice into wedges and serve. Pairs well with vanilla ice cream or whipped cream.