To begin, preheat the oven to a temperature of 350 degrees Fahrenheit (175 degrees Celsius), and make sure to prepare a 9-inch springform pan by greasing and flouring it thoroughly.
take a large mixing bowl and use an electric mixer to beat together the egg yolks and sugar until the mixture becomes fluffy. Then, add in the carrots, almonds, lemon juice, and lemon zest, and continue to beat everything together until the ingredients are fully combined.
In a separate bowl, mix together the flour, baking powder, and salt, and then gradually add these dry ingredients to the egg and sugar mixture, stirring everything together until a smooth batter is formed.
In another bowl, beat the egg whites until they form stiff peaks, using a glass, metal, or ceramic bowl for best results. Then, use a spatula to gently fold the egg whites into the cake batter, being careful not to overmix.
Once the batter is fully combined, pour it into the prepared springform pan, and bake in the preheated oven for between 40 and 50 minutes, or until a toothpick inserted into the center of the cake comes out clean. After removing the cake from the oven, allow it to cool on a wire rack for 5 minutes, then use a table knife to loosen the edges before carefully removing the cake from the pan and placing it on a serving plate or cooling rack to cool for an additional 30 minutes.
While the cake cools, knead the marzipan until it is soft and pliable, then separate 1/5 of the marzipan and add a small amount of green food coloring using a toothpick, kneading the marzipan until it is uniformly green. Use the same method to color the remaining marzipan orange, then shape the orange marzipan into 12 small carrots, using a paring knife to create tiny indentations on top. Shape the green marzipan into little leaves and stick two leaves onto the top of each carrot using a small amount of water.
To finish the cake, combine confectioners' sugar with enough lemon juice to make a thick icing, and use it to coat the cake. Then, place the marzipan carrots on top around the edges of the cake, making sure that each piece of cake has a marzipan carrot. Allow the icing to dry completely before slicing and serving the cake.
