Preheat your oven to 350°F (175°C) and grease a bundt pan.

In a stand mixer, beat egg yolks and sugar until pale yellow, about 3-4 minutes, then add sweetened chestnut purée and vanilla extract.

Pour in melted butter and mix on low until combined.

Whisk together flour, cocoa powder, baking powder, and salt in a separate bowl.

Gradually add dry ingredients to wet, alternating with milk.

Whip egg whites to stiff peaks and gently fold into batter.

Pour batter into bundt pan and bake for 50-60 minutes until a skewer comes out clean.

Cool bundt cake in pan for 5 minutes, then invert onto a wire rack to cool completely.

For candied chestnuts, melt butter in a skillet, add chopped roasted chestnuts and sugar, cooking until caramelized.

For ganache, place chopped dark chocolate in a bowl, heat cream until boiling and pour over chocolate, whisk until smooth.

Once cake is cool, pour ganache over the top and garnish with candied chestnuts.