Preheat Oven: Preheat the oven to 350°F and generously grease 9x13" baking pan. Set aside.
Mix Wet Ingredients: Add the sugar and butter to a large bowl and mix on medium-high speed until smooth and creamy. Add the egg yolks, one at a time, while continuing to mix. Add the cognac and mix until blended in.
Mix Dry Ingredients: In another large bowl, combine the walnuts, breadcrumbs, baking powder, cinnamon, nutmeg, cloves and salt.
Combine Wet & Dry Ingredients: Add the dry ingredients to the wet ingredients and mix until well combined and smooth.
Add Egg Whites: Add the egg whites to another bowl and mix until stiff peaks form. Fold in the egg whites into the cake batter, a quarter at a time, with circular movements until finished.
Bake: Pour the cake batter into the greased pan and transfer to the preheated oven. Bake for about 35 minutes, or until the cake is nicely browned. Test with a toothpick to make sure it's baked through.
Make Syrup: While the cake is baking, make the syrup. Add all the syrup ingredients together to a small saucepan and boil until the sugar is dissolved, stirring occasionally, over medium heat. Turn the heat down to medium-low and simmer the syrup for 5 minutes. Remove the cinnamon stick and cloves. Let the syrup cool while the cake is baking.
Finish: As soon as the cake comes out of the oven, pour the cooled syrup over the entire cake. You could also pour hot syrup on a cool cake. Allow the cake to absorb all the syrup.
Serve: Cut the cake into diamond shaped pieces and serve with walnut half on top and a scoop of vanilla ice cream.