-
1
Lightly coat an 8-inch round cake pan with oil, and line with plastic, leaving a 4-inch overhang.
-
2
Finely grind chestnuts in a food processor.
-
3
Heat ground chestnuts, milk, 3 tablespoons sugar, and the salt in a medium saucepan over medium-high heat, stirring occasionally, until bubbles form at edge.
-
4
Whisk together yolks, cornstarch, and remaining 2 tablespoons sugar in a medium heatproof bowl.
-
5
Slowly add hot chestnut mixture to yolk mixture, whisking constantly.
-
6
Return to pan; cook over medium-low heat, whisking constantly, until thick, about 2 minutes.
-
7
Transfer to the bowl of a mixer.
-
8
Add vanilla and butter.
-
9
Beat on medium speed until cool, about 5 minutes.
-
10
Stir half the chestnut mixture into melted chocolate.
-
11
Beat 1 1/4 cups cream until soft peaks form.
-
12
Using a rubber spatula, gently fold half the whipped cream into plain chestnut mixture and the other half into chocolate-chestnut mixture.
-
13
Pour chestnut mousse into prepared pan.
-
14
Cover with 12 chocolate wafers, working in a circular pattern.
-
15
Top with chocolate-chestnut mousse and remaining 12 chocolate wafers.
-
16
Fold plastic overhang over top to cover cake.
-
17
Refrigerate overnight.
-
18
Uncover cake; place a platter on top, flip, and unmold.
-
19
Remove plastic.
-
20
Beat remaining 1/4 cup cream until soft peaks form.
-
21
Spread on top of cake.
-
22
Garnish with chocolate shavings.
