Heat oven to 350 degrees. Oil the baking dish bottom and sides and set aside. Tip: To ensure the finished cake comes away easily from the pan, after oiling the pan, I cover the bottom with parchment or wax paper, and lightly oil that as well.
Whisk the egg whites until stiff but not dry, and set aside.
In a medium bowl, combine egg yolks and sugar, and whisk to blend. Whisk in almond extract, oil and orange zest or extract (if using). Add the cardamom (or spice mixture) to the almond flour and mix until the spice(s) are distributed evenly. Add to the egg and sugar mixture and stir to combine. Gently stir a third of the whites into the batter, then gently fold in the rest until just incorporated.
Pour batter into prepared pan. Bake until a toothpick inserted in the center comes out clean, about 50 minutes. Allow to cool for 10 minutes, then remove from pan and finish cooling on a rack. To decorate, dust with confectioners’ sugar and chopped pistachios. Delicious on it's own, or with some fresh fruit alongside.