The Best Chocolate Cake in the World

The afternoon before

Prepare the first stage of the filling mousse and the coating.

1. Chop all the chocolate and place it in a bowl.
2. Place the melted butter for the final coating in another bowl.
3. Heat the cream in a saucepan and, when it comes to a boil, remove it from the heat and pour it into the bowl of chocolate.
4. Stir well until the mixture is fully combined.
5. Transfer 1/3 of the chocolate to the bowl of melted butter, add the small amount of water and stir until completely smooth.
6. Cover the preparation with plastic wrap touching the chocolate.
7. Let it come to room temperature and refrigerate until the next day.
8. Refrigerate the remaining 2/3 of the chocolate until the next day.

The evening before

Bake the meringue for the cake layers.

1. Preheat the oven to 200 ºC.
2. Prepare a flat baking sheet and the oven rack.
3. Using a pencil, draw 3 circles about 15 cm in diameter on baking paper.
4. Place the paper on the baking sheet with the drawing underneath, so that the pencil graphite does not touch the meringue.
5. Whip the egg whites at low speed and, when they begin to foam, gradually add the icing sugar and then the small amount of cornstarch.
6. When the meringue is very white, firm and glossy, add the cocoa powder.
7. Transfer the meringue to a piping bag and fill the circles, forming a spiral from the center out to the edges.
8. Make sure the meringue discs fit the drawn circles.
9. Lower the oven temperature to 130 ºC.
10. Bake them for 3 hours.
11. Do not open the oven door at any point during baking.
12. Turn off the oven and keep the door closed.
13. Let the meringues cool inside the oven, with the door closed, until the next day.

The next day

Prepare the filling mousse.

1. Whip the egg whites with the icing sugar until they form stiff peaks.
2. Remove the bowl with the 2/3 of the chocolate from the refrigerator, stir it well with a fork and then whip it with electric beaters.
3. Gradually fold the egg whites into the chocolate using a rubber spatula and gentle folding motions.

Assembling the cake

1. Place a sheet of baking paper on a flat plate.
2. Place a first meringue base with the flat side underneath.
3. Fill it with a layer of mousse; there must be some left to make another layer and to cover the sides and surface.
4. Place the second meringue base and fill it with mousse.
5. Place the third meringue base with the flat side facing up.
6. Spread mousse on the top to cover any irregularities and try to smooth the sides by applying mousse with the spatula.
7. Refrigerate the cake for at least one hour so that it cools and firms up.

Preparing the cake coating

1. Place a rack over a plate to collect the excess chocolate from the final coating.
2. Carefully heat 1/3 of the coating chocolate until it reaches 45 ºC, without exceeding this temperature.
3. Then cool it to 32 ºC-31 ºC.
4. To cool it, pour half of the chocolate onto marble and spread it with a spatula until it reaches a thick consistency; then return it to the bowl containing the other half and stir well. You can also cool the bowl of chocolate in a cold water bath while stirring and checking its temperature.
5. When the coating drops to 32 ºC-31 ºC, remove the cake from the refrigerator and place it on the rack.
6. Pour the coating over the top, from the center toward the edges, forming circles.
7. Thin the coating layer by passing a long knife over it.
8. Optionally place sliced almonds on the top and sides to disguise any irregularities.
9. Let it come to room temperature until the coating sets.
10. You can leave the cake in the refrigerator until lunch begins.
11. If you need to serve it the next day, refrigerate it and take it out one hour before eating.