Preheat oven to 180 degrees C (350 degrees F). Line a 18 cm (7 inch) cake pan with a circle of parchment paper. Grease well the pan on top of the paper and around the sides.

In a bowl combine spelt flour, ground almonds, ground hazelnuts, baking powder, cinnamon and nutmeg.

In a mixing bowl beat the eggs until thick and foamy. Add honey and beat until combined. Add oil and vanilla and beat again shortly, until smooth.

Using a wooden spoon fold in the dry ingredients. Add the grated carrots and mix gently to distribute them evenly around the batter.

Let the cake cool 10 minutes in the pan and then remove it after carefully running a knife around the edges. Let cool until room temperature before assembling.

Combine all ingredients in a large bowl. Beat with an electric mixer until fluffy.

Using a long serrated knife cut the cake horizontally in two layers. Place one layer on a serving plate and cover with ⅓ of the frosting. Place on top the second layer. Cover the cake on top and all around with the remaining frosting.