Preheat oven to 180 degrees C (350 degrees F). Line a 18 cm cake pan with a circle of baking paper. Grease well the pan.

In a bowl combine spelt flour, chestnut flour and baking powder. Mix to blend and set aside.

In a large mixing bowl beat eggs and the two kinds of sugar for 5-6 minutes, until the mixture gets thickens and increases its volume significantly. Add vanilla extract, beer and oil and beat shortly until absorbed.

Gradually add the dry ingredients, mixing gently with a rubber spatula, until incorporated.

Transfer the batter to the prepared pan. Bake for about 40 minutes or until a wooden skewer inserted in the centre comes out clean. Let cool until room temperature before assembling the cake.

In a small saucepan over medium heat combine chestnut flour, sugar and milk. Stir with a hand whisk until there are no more crumbs and the mixture begins to simmer. Lower the heat and keep stirring until the mixture starts thickening. Let cool until room temperature. You can even cool it in the fridge but it shouldn’t be warm!

In a large bowl beat together butter and vanilla until light and fluffy. Gradually add the chestnut flour mixture and keep beating until a fluffy and smooth texture.

With a long serrated knife cut the cake horizontally in three equal layers (you can refrigerate the cake for easier cutting). Place one layer on a serving plate and cover with ⅓ of the frosting. Place another layer on top and cover with another ⅓ of the frosting. Finish with the third layer. Cover the cake all around with a thin coat of frosting. Decorate with chocolates and candied chestnuts.