Begin by melting 80 grams of butter in a medium saucepan over low heat. Whisk in 100 ml of milk, 100 ml of water, and ½ teaspoon of salt until well combined.

In a separate large mixing bowl, sift together 500 grams of flour and 1 teaspoon of baking powder.

Pour the dry ingredients into the saucepan and stir vigorously until a smooth dough forms. Allow to cool slightly for about 5 minutes before adding eggs one at a time.

Preheat your oven to 400°F (200°C). Divide the dough into two portions and spread evenly into greased baking pans. Bake for about 20 minutes until lightly golden.

In a mixing bowl, beat together 4 eggs and 150 grams of sugar until frothy. Gradually add 100 ml of milk and a couple of tablespoons of flour, stirring to avoid lumps. Cook over medium heat until thickened.

Once both layers and cream filling have cooled, assemble the cake by placing one layer on a plate, spreading half of the cream filling, adding the second layer, and topping with the remaining filling.

Refrigerate for at least two hours. Before serving, dust with icing sugar or garnish with fruits or chocolate shavings.