Arrange oven racks to divide oven into thirds. Preheat oven to 180C. Grease two 22cm cake pans, dust with a spoonful of flour and tap out. Line each with a round of parchment paper.
Sift together flour, baking powder, baking soda, cinnamon and salt into a bowl. In another bowl, stir together carrots, curgettes, beets and raisins.
In a large mixing bowl, beat maple syrup and oil together until emulsified. Add eggs one at a time, beating until batter is smooth. Add flour mixture in three or four batches, mixing gently until mixture is even. Gently mix in the vegetable mixture. Divide between baking pans.
Place one baking pan in center of each of the racks. Bake 25-35 minutes, until a skewer or paring knife inserted into centers comes out clear and cakes are pulling away from the sides of pans. Cool on a rack about 5 minutes, then gently remove from pans. Cool to room temperature before frosting.
To make frosting: Place avocado and cocoa powder in a food processor and blend together until smooth. Keep blending until the mousse is very smooth and creamy. Taste, and if you would like it a little sweeter, you can add a bit of honey or maple syrup.
You can divide your cake in two and spread some avocado chocolate muss between layers.
