Preheat your oven to 350 degrees. Then, generously butter and flour your cake pan of choice (9 inch square pan would be perfect!). Beat the egg yolks and rapadura together in a mixer for a few minutes, then add in the lemon zest, almond extract, carrots, ground almonds, arrowroot and sea salt.
In a separate, clean bowl, beat together the egg whites and a small pinch of sea salt until stiff.
Gently fold the egg whites into the almond mixture. Fold, people. Gently fold. Don't mix. Fold.
Pour into your buttered/floured cake pan. Sprinkle your chopped walnuts on top of the cake and bake for about 45 minutes, until nice and golden. Once it's cooled, you can remove it from the pan, and eat to your hearts content.