½ cup + 1 ½ tablespoons confectioners sugar, divided, plus extra for dusting
1 ½ cups whipping cream
Directions
To make the meringues, preheat the oven to 300 F. Using two of the eggs, separate the egg yolks from the egg whites. Store the egg yolks in the fridge in a sealed container for another recipe.
Using a stand mixer or a handheld whisk, add the two egg whites to a clean bowl and then add the cream of tartar if using. Beat the egg whites on high until they are foamy, and then gradually add ½ cup of granulated sugar to the bowl, one tablespoon at a time. Beat the mixture thoroughly for at least 30 seconds between each addition. The meringue mixture is ready when it forms stiff peaks, and no longer feels grainy when rubbed between your finger and thumb.
Transfer the meringue mixture to a piping bag fitted with a large, round nozzle, and then pipe out small cones of meringue onto a prepared baking tray. The base of the meringues should be roughly 1 ½ to two inches wide.
When the meringues are placed into the oven, drop the temperature immediately to 275F and let them cook for 30 minutes. Then turn off the oven and leave the meringues to sit in the oven until it is cold (around 3 hours).
To make the chestnut paste add the whole cooked chestnuts to a food processor along with the cream, ½ cup of confectioner's sugar, and 4 tablespoons of cold water. Blend everything until it is smooth, and then press the chestnut mixture through a fine mesh sieve to remove any remaining lumps. Cover and set to one side.
To make the vanilla cake base, preheat the oven to 350 F and line a 9 x 13 inch baking sheet with baking paper.
Sift together the flour, baking powder, and salt in a medium-sized bowl.
Using a stand mixer or electric whisk, beat ½ cup of granulated sugar and the butter together for 3 to 4 minutes until it is thoroughly creamed. Beat in the two eggs and the vanilla extract.
Add half of the flour mixture to the mixer and beat until just combined. Then add the milk and mix everything again, before adding the remaining flour. Fold everything together until it is just combined, and then spread it onto the prepared baking sheet.
Bake the cake base for 20 minutes, until it is risen and springs back to the touch. Remove it from the oven and set it aside to cool completely.
Add the whipping cream to a bowl or stand mixer, along with 1 ½ tablespoons of confectioner's sugar. Beat the cream and sugar until it is just whipped.
Using a 2 ½ inch round cookie cutter, cut out eight circles from the cooled vanilla cake; these cake rounds will serve as the base for your Mont Blancs.
To assemble the cakes, transfer the whipped cream to a piping bag with a large round nozzle, and transfer the chestnut mixture to another piping bag with a small round nozzle.
Start by piping a tablespoon of cream into the center of each cake round, and then place a meringue on top. Finish by piping another small swirl of cream on top of the meringues.
Place one of the cakes onto a cake turntable and then slowly pipe the chestnut purée around the cream and the meringue, to eventually make a cone shape concealing them inside the cake. These do not need to be perfectly formed, as they are meant to resemble a mountain top.
Repeat this process with all of the cake bases. Finish off by sprinkling the Mont blancs with a dusting of confectioners sugar, and add a few cocoa nibs to the tips of each cake if desired.