Winter Chestnut Cognac Cake with Caramel Buttercream

Drain the cooked chestnuts in a sieve and let cool completely. Process with an immersion blender or food processor until you have a smooth, creamy purée without any lumps.

Preheat oven to 175°C (350°F). Grease a 26cm (10-inch) springform pan and dust with flour. Cream butter with brown sugar until light and fluffy. Beat in eggs one at a time, then mix in cognac and chestnut purée.

Combine flour, baking powder, cinnamon, and salt. Alternately fold the flour mixture and milk into the butter mixture, beginning and ending with flour. Mix just until combined.

Pour batter into prepared pan and spread evenly. Bake for 50-55 minutes until a wooden skewer inserted in center comes out clean. Cool in pan for 10 minutes, then turn out and cool completely.

Melt sugar in a heavy-bottomed pan over medium heat without stirring. When sugar turns light amber, swirl the pan. Carefully pour in cream (it will splatter!), then add a pinch of salt. Stir until smooth. Let cool completely.

Beat soft butter until fluffy. Gradually beat in cooled caramel until smooth. Mix in cognac. The buttercream should be spreadable but firm enough for piping.

Cut the cooled cake in half horizontally. Spread half the buttercream on the bottom layer. Place top layer and frost entire cake with remaining buttercream or pipe decoratively.

Refrigerate assembled cake for at least 3 hours to allow flavors to meld. Remove from refrigerator 30 minutes before serving to let buttercream reach proper consistency.