CHOCOLATE CHESTNUT COOKIE CAKE

Thin layers of ganache and chestnut buttercream between buttery, vanilla flavored cookie layers… aaah! I ordered French unsweetened "chestnut puree". This is simply an unflavored, unsweetened chestnut mush in a can, and not to be confused with the iconic Hungarian dessert, Chestnut Puree. I used half of a 439g can for this recipe. On the off chance you just made THE dessert and it is flavored and sweetened already, and happen to have 1/2 cup left, this can also serve as the base for the small amount of chestnut puree required for the buttercream. Keep in mind, the dessert is already plenty sweet, so use the icing sugar for the buttercream with restraint. Chestnut flavor is truly, truly a unique experience, but in a pinch, unsweetened hazelnut butter, please no Nutella, is the logical substitute. Chestnut and hazelnut both pair well with ganache. Make the cookie slab first and the ganache and chestnut buttercream next. Assemble the cake, chill and enjoy. 

CHOCOLATE CHESTNUT COOKIE CAKE 

Vanilla Cookie Slab: 

3/4 cup butter, soft 

1-1/4 cups icing sugar 

dash of salt 

2 egg yolks 

1-1/2 tsp pure vanilla extract 

2 cups flour 

1/8 cup cornstarch 

3 Tbsp 14% sour cream 

Chocolate Ganache: 

6oz bittersweet pure chocolate 

2 Tbsp oil 

1/3 cup whipping cream 

Chestnut Buttercream: 

1/2 cup unsalted butter 

2 cups icing sugar, sifted 

220g unsweetened chestnut puree 

1/8 cup whipping cream 

2 Tbsp dark rum or rum extract 

 

Preheat the oven to 400F.

In a medium bowl, on high speed, cream the butter and the sugar. 

Add the salt. Stir in the egg yolks and vanilla extract. 

Reduce speed and start adding the flour. 

Keep beating until smooth dough forms. 

Line a large flat cookie pan with parchment and roll out the dough on top. 

Poke it with a fork and bake it in preheated oven for 8 minutes. 

Remove from oven and while still hot, parallel with the short side of the pan cut the cookie into 4 even strips. 

Next, find the middle of the short side of the pan and cut across parallel with the long side of the pan. Now you have 8 cookie strips. 

Let the strips cool down to room temperature before handling. 

Meanwhile make the chocolate ganache first. 

 Chop the bittersweet chocolate and partially melt it in the microwave. 

Stir it until fully melts. 

Add the oil and add the whipping cream and stir to combine. 

Next make the chestnut buttercream. 

On low medium speed, beat the soft butter, gradually adding the icing sugar until combined. 

Switch to high speed and beat the buttercream for 6 minutes. 

Add the chestnut puree and the rum extract. 

Beat for 2 minutes longer until the ingredients are fully incorporated. 

To assemble the cake, spread the layers alternating with ganache and chestnut buttercream, making sure ganache is on the top. 

Place the cake in the fridge for the night, slice and enjoy it the following day.