First, prepare the syrup. Place all syrup ingredients in a small saucepan and bring to a boil. Simmer on medium high for 15 minutes. Remove from heat and let the syrup return to room temperature while you are preparing the cake.
Preheat your oven to 350 degrees F. Place matzo meal in the food processor. Process until the matzo crumbs become powdery fine (about 1 minute). Add walnuts and almonds to the food processor and process for another 45 seconds, until nuts are ground very fine and mixed well with the matzo powder.
In a separate mixing bowl, whip 5 eggs with a hand mixer or immersion blender. Add sugar, orange zest, orange juice, cinnamon, nutmeg and 1 tbsp of walnut or almond oil to the bowl. Continue whipping till mixture is well blended and frothy. Add egg liquid to the food processor. Process the matzo and liquid together for about 1 minute, until it is well mixed and the texture resembles Play-doh.
Liberally grease 8x8 inch baking dish with remaining walnut or almond oil. Press the cake dough firmly into the dish until it forms a shallow cake. Make the cake as even as possible across the top; you can use a flat silicone spatula to help you flatten it out.
Traditionally, this cake is served in diamond-shaped pieces. Cut the cake into diamonds by slicing the dough crosswise, then making diagonal cuts across the rows, like this:
Or you can cut it into squares if you prefer. Optional: Garnish the center of each piece with a whole almond.
After slicing, place cake in the oven and bake for 30-35 minutes, until top is firm and edges are browned. Test for doneness with a toothpick.
Remove cake from oven. Run your knife through the cuts again, making sure the slices go all the way through the cooked cake to the very edges (if you have a glass baking dish, you’ll be able to see the cuts better). Pour the room temperature syrup evenly over the freshly baked cake. Cover with foil and allow the cake to absorb the syrup for at least 2 hours—if you can leave it overnight, even better. The syrup will keep the cake moistened, not soggy. Will keep for several days.
I like to serve each piece of cake on top of two sliced fresh orange rings. Sometimes I make a little extra syrup and soak the orange rings in that before plating the dessert. Enjoy!