Russian Napoleon Cake with Silky Custard | 1H 45M

Instructions:

1. Combine the 450g flour and 400g cold cubed butter on a large surface. Pulse in a food processor or use a pastry cutter until the mixture resembles coarse crumbs.
2. Whisk the 150ml cold water, 1 egg, 1 tbsp vinegar, and salt together. Pour this into the flour mixture and fold gently Note: Do not overwork the dough; you want visible streaks of butter.
3. Divide the dough into 12 equal portions, wrap them, and chill for at least 1 hour. Wait until the dough feels firm to the touch.
4. While the dough chills, whisk the 4 egg yolks, 200g sugar, and 60g cornstarch in a saucepan. Gradually whisk in the 1 liter of milk until the mixture is smooth and pale.
5. Cook the custard over medium heat, stirring constantly, until it thickens and the first bubbles break the surface. Remove from heat and stir in the 200g condensed milk and vanilla.
6. Preheat your oven to 200°C (400°F). Roll each dough ball out on parchment paper into a very thin circle, roughly 9 inches across.
7. Prick the dough all over with a fork. Bake each layer for 5-7 minutes until golden and crackling. Repeat for all layers, plus any scraps for crumbs.
8. Once the custard base is completely cold, cream the 200g of softened butter. Gradually whisk the custard into the butter 1 tablespoon at a time until a velvety, thick cream forms.
9. Stack the layers, spreading about 4 tablespoons of cream between each one. Press down gently with each new layer to ensure even contact.
10. Coat the top and sides with the remaining cream. Crush the extra baked pastry scraps into fine dust and press the crumbs firmly onto the exterior.