Set up a double boiler and add 3 inches of water in a small saucepan. Get a heat-safe bowl that will fit perfectly on top. Bring the water to a gentle boil. Whisk the egg yolks and ¼ cup sugar in the heat-safe bowl and add it on top of the pot of simmering water.
Cook this mixture for about 5 minutes as you whisk constantly, until the sugar dissolves. Add the brandy (optional) and continue cooking for about 10 minutes while whisking until the mixture turns light and foamy.
Remove the heat-safe bowl from the heat and add both the chocolate and peppermint extract. Allow it to sit for 5 minutes, or until the chocolate is fully melted, then whisk it until smooth. If the chocolate does not fully melt when it's out of the fire, return the bowl to the double boiler and whisk it until fully melted then set it aside
In a stand mixer, beat the heavy cream with the remaining sugar and scrape it into a large bowl and set it aside.
Meanwhile, add the mascarpone cheese to the same mixer bowl and fit the mixer with the paddle attachment. Add the chocolate mixture to the cheese and beat it for 2 minutes. Once it is well mixed, remove the mixer bowl from the mixer and fold the whipped cream in half. Set the remaining whipped cream in the fridge.
Prepare the ladyfingers by dipping them to a hot coffee in a shallow bowl. Allow them to soak for about 1-2 seconds. Make a layer and allow it to soak for about 1-2 seconds.
Make a layer of ladyfingers at the bottom of the baking dish, and top it up with half of the mascarpone mixture. Repeat with remaining ladyfingers and mascarpone. For the final top layer, top it with an even layer of the remaining whipped cream. Use plastic wrap to cover tightly and allow it to sit in the fridge overnight.
When ready to serve, dust it with cocoa powder, chocolate curls, and crushed peppermint candies.
Serve cold.