Grate the zest of an orange and set it aside. If planning to decorate with the caramel, place the peeled oranges in a small pot, cover with water and bring to a boil. Simmer for about 30-40 minutes, covered (skip this step if decorating with orange marmalade).

Beat the egg yolks and 2 whites with the sugar and the salt until frothy. Add the ground almonds and the matzah meal, the zest of one orange , the liqueur if using, and combine well. In a separate bowl beat the whites with an electric whisk until stiff; gently incorporate them into the batter with a spatula, using an upward motion. Grease the sides of a baking pan and dust with matzah meal, and line the bottom with parchment.

In a pre-heated oven, bake at 350 F f(on a regular – NOT convection – setting) for 30 minutes, then lower the heat slightly (to 335 or 340) and cook for another 20 to 30 minutes (50-60 total), checking periodically with a toothpick until the cake is moist but not liquid inside. Once the top is golden, you may want to cover it with foil for the last part of the cooking. Once the cake is done, turn off the oven setting the door slightly ajar and allow the cake to rest inside for an extra 15 minutes (similarly to what you would do with a cheesecake!). Remove from the oven and allow to cool down completely. In the meantime, melt the remaining ½ sugar with 1/2 cup of the water in which you boiled the orange. You can double the dosage for a thicker layer. Make sure to use low heat, stirring constantly, until it forms a caramel. Stir in the remaining shredded zest of the first orange, and brush on top of the cake. Decorate with sliced or slivered almonds. If you don’t feel like making the caramel, you can just glaze the top of the cake with about 4-5 tablespoons of orange marmalade diluted with 2 tbsp hot water.

* For those of you who love oranges, there is also a version of this cake that incorporates the boiled pulp of the 2 oranges into the batter. The recipe is pretty much the same, except that you should use only 4 yolks (beaten with the sugar), and 4 egg whites (beaten stiff). After removing most of the white membranes, place the cooked oranges into a blender, and add them to the batter. Other than that, proceed in the same way. Because the cake will be much more "orangey", you can decorate it with simple powdered sugar.