You've made the chestnut cake layers and the frosting. Now comes the fun part:
Spread 3/4 cup chestnut frosting on top of first cake layer. Repeat with second layer and another 3/4 cup chestnut frosting. Top with final layer. Coat top and sides with 1 cup chestnut frosting. Refrigerate 30 minutes. Coat cake with chocolate frosting, then decorate as shown below.
1. With a small offset spatula at a slight angle, scrape frosting down in strips to resemble bark, flaring at base.
2. Top with a scant 1/2 cup chestnut frosting, then make a fine, tight spiral in frosting with spatula, as shown, turning cake as you work.
3. Add thin smears of chestnut frosting to sides, working from top to bottom.
Finished cake should be refrigerated for at least 30 minutes and up to 3 days. Bring to room temperature before garnishing with woodland decorations (see our favorites), and serving.