Preheat the oven to 350 degrees Fahrenheit, then grease a 9-inch cake pan with cooking spray or with oil or melted butter. Line the bottom of the pan with parchment paper. Grease the paper. Set aside.
In the bowl of a stand mixer fitted with the whisk attachment or with an electric mixer, whisk the egg whites until stiff peaks form, about 4 minutes. Set aside.
In a separate medium sized bowl, combine the egg yolks and sugar and whisk to blend. Stir in the almond and vanilla extracts, oil and the orange zest.
Add the almond flour and the ground cardamom and mix to combine. The cake batter will look very dense.
Gently, fold about 1/3 of the egg whites into the almond cake batter until combined.
Add another third of the whites and fold until just combined. Add the remaining whites and fold just until incorporated, scraping the bottom and sides of the mixer to make sure the ingredients are evenly combined
Pour the batter into the prepared pan and bake for 40 to 45 minutes or until a cake tester or toothpick inserted in the middle comes out clean.
Remove from the oven and allow the cake to rest for 10 minutes. Run a knife or thin spatula around the sides of the cake and remove from the pan.
Dust with powdered sugar and garnish with almonds. Serve.