Spread the hazelnuts on a baking sheet. Bake until fragrant, about 10 minutes. Rub the warm hazelnuts in a clean kitchen towel to remove the skins.
Reduce the oven temperature to 300 degrees F. Grease a 9-inch springform pan with butter, then fit with a circle of parchment paper, and brush the parchment with butter.
Combine the hazelnuts, brandy, cherries, unsweetened chocolate and bittersweet chocolate in a medium bowl. Sift 1 cup of the flour and 1/2 teaspoon of the cinnamon in another bowl.
Combine the honey and sugar in a saucepan. Stirring constantly, bring the mixture to a boil, then reduce the heat and simmer for 2 minutes. Add the dried fruit mixture, stirring until combined. Fold in the flour and mix to combine. Pour into the prepared pan.
Use wet hands or a small metal spatula to press the mixture to form a level layer. Combine the remaining 1/2 tablespoon flour, 1 teaspoon cinnamon and the cocoa. Sift over the cake. Bake until set, about 30 minutes.
Cool and gently brush off the flour coating before serving.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.