Three Milk Cake with Dulce de Leche Glaze

Ingredients:

Cake

• 6 large eggs, room temperature
• 0.5 tsp. potassium hydrogen tartrate (cream of tartar)
• 1 cup of sugar
• 1 tbsp + 1 tsp vanilla extract
• 1 cup of flour, level, scoop with a spoon
• 1/4 tsp baking powder
• 1/4 teaspoon fine salt
• 400 g sweet condensed milk
• 340 gr. concentrated milk
• 1 cup heavy cream

Glaze

• 1 and 1/4 cups sugar
• 3 large egg whites, room temperature
• 1 teaspoon vanilla extract
• 0.5 tsp. potassium hydrogen tartrate (cream of tartar)
• A pinch of fine salt
• 3 tbsp. ready Dulce de leche or boiled condensed milk
• Special equipment: 25cm cake pan with a hole in the centre (not with a removable bottom), long skewer

Preparation:

1. Cake: Preheat the oven to 175°C. Separate the egg yolks from the whites. Pour the whites into one large bowl and the yolks into another.
2. Add the cream of tartar to the egg whites in a bowl and beat with an electric mixer on medium-high speed until soft peaks form, about 3 minutes. Reduce the mixer speed to low and gradually beat in 1/3 cup of sugar. Once the sugar is fully incorporated, reduce the speed back to medium-high and continue beating for about 4 minutes, until stiff, glossy peaks form.
3. Add the remaining sugar and 1 tablespoon vanilla extract to the bowl with the egg yolks and beat with a mixer for about 5 minutes, until the mixture turns pale yellow and very thick. If you drop a small amount of batter back into the bowl, it should float on the surface for a few seconds before it merges with the rest of the batter. Sift the flour, baking powder, and salt into the resulting mixture and mix until combined. Fold in about 1/3 of the egg whites to give the batter a lighter texture. Fold in the remaining whites in 2 additions until the batter is smooth and streak-free. Pour into an ungreased 25cm cake pan.
4. Bake for about 35 minutes, until the cake is golden brown and springs back when lightly pressed. Immediately place the cake pan on a cooling rack and leave it there until the cake is completely cool. Using a thin spatula, run around the perimeter of the pan and around the inner ring; gently working around the cake, gradually pull it out of the pan. Scrape any crumbs from the bottom and sides of the pan (it doesn't have to be perfectly clean, but you don't want any extra crumbs soaking up the milk mixture), then return the cake to the pan.
5. Using a long skewer, poke holes all over the cake (about 60 should be enough), piercing it all the way through so the skewer reaches the bottom of the pan. In a medium bowl, whisk together the condensed milk, evaporated milk, cream, and the remaining 1 teaspoon of vanilla extract. Slowly pour the mixture over the cake, letting it drip down the sides, making sure it evenly coats the cake. (It may seem like too much liquid, but it will eventually be completely absorbed.) Cover and refrigerate for at least 6 hours or overnight.
6. One hour before serving, remove the cake from the refrigerator and let it stand at room temperature to warm up a little.
7. Glaze: Meanwhile, bring 3–4 inches of water to a simmer in a medium saucepan. Place a large stainless steel bowl on top of the saucepan (do not let it touch the water); add the sugar, egg whites, 1/4 cup cold water, vanilla extract, cream of tartar, and salt, and whisk until combined. Then, with the bowl in the double boiler, beat the mixture with an electric mixer on medium-high speed until stiff, glossy peaks form, 5–7 minutes. Remove the bowl from the heat and let it sit for a few minutes.
8. Assembly: Using a thin spatula, run the icing around the perimeter of the pan and around the inner ring, gently pulling the cake to release it from the pan. Invert the pan, pressing it onto the rimmed plate. Using a small offset spatula or spoon, generously spread the icing over the top, sides, and inside of the cake. In a small bowl, microwave the dulce de leche sauce until it's thin enough to pour, about 8 seconds. Drizzle the dulce de leche over the top of the cake, letting it drip down the sides.