Position a rack in the middle of the oven. Heat the oven to 325°F. Generously oil an 8x2-inch round cake pan (or an 8-1/2-inch springform pan) with olive oil and line the bottom of the pan with parchment or waxed paper. Oil the paper and dust it lightly with flour.
In a small saucepan, boil about 1/2 cup of water. Meanwhile, sift the cocoa powder through a strainer over a small bowl. Stir 6 Tbs. of the boiling water into the cocoa until it's smooth and glossy (if the mixture is very thick, you can add as much as 2 Tbs. more boiling water; when I tried this cake with Hershey's cocoa, I needed to do this). Stir in the vanilla and almond extracts. Set aside to cool slightly. In another small bowl, mix together the flour, salt, and baking soda and set aside.
In the bowl of a stand mixer, combine the eggs and yolk, olive oil, and sugar. Using the whisk attachment, beat on medium-high speed until thick, lemon colored, and creamy, 2 to 3 minutes, scraping down the sides of the bowl. Reduce the speed to low and gradually add the warm (not hot) cocoa mixture until it's well combined, scraping down the sides of the bowl once. Gradually mix in the dry ingredients until just combined, scraping down the sides of the bowl.
Pour the batter into the prepared cake pan and bake in the center of the oven until a toothpick comes out with a few moist crumbs clinging to it but with no wet batter, 55 to 60 minutes. Put the pan on a rack and carefully run a paring knife around the inside edge to release the cake. Let cool for 10 minutes. Using a second rack to sandwich the cake pan, flip the pan over. Carefully lift the pan from the cake, gently peel off and discard the paper liner, and let the cake cool completely.
Before serving, dust the top of the cake with confectioners' sugar. To use a stencil pattern, use the flat side of the cake for a more level surface (the cake may dip slightly in the center; if that's the case, you'll get a cleaner design with a pattern that keeps close to the perimeter).