Custard-filled Basque cake

Let the butter portion for the dough soften. Separate 7 eggs. Reserve 3 yolks for the custard and keep the remaining whole egg. Mix 200 g soft butter with 150 g sugar. Beat in the other 4 yolks and 10 ml rum. Add 300 g flour and the baking powder and mix just until smooth. Flatten, cover and chill for about 60 minutes.

Split the vanilla pod and scrape out the seeds. Heat the milk with the pod and seeds until simmering. Whisk the reserved yolks and whole egg with the reserved 80 g sugar and mix in 40 g flour. Remove the pod and gradually whisk in the milk. Cook over a low heat, stirring until thick and the first bubbles appear. Add the reserved 10 ml rum. Spread in a dish, cover the surface and cool.

Grease a 24 cm round tin with the reserved 10 g butter. Dust with some of the reserved 10 g flour and use the rest on the work surface. Roll out slightly more than half the pastry to line the base and sides. Add the cooled custard. Roll out the remaining pastry, lay it over the custard and carefully seal the edges. Lightly mark the top with a fork.

Heat the oven to 180 °C. Bake for about 45 minutes until golden and cooked around the edges. Cool completely in the tin for about 180 minutes before unmoulding so that the filling and pastry firm up.