Preheat oven to 350°F/175°C. Coat 2, 8- or 9-inch round cake pans with vegetable cooking spray. Cut parchment paper into two 8- or 9-inch circles. Place the round parchment paper in the bottom of the pans. Spray papers with vegetable cooking spray. Set aside.
In the bowl of your stand mixer fitted with the paddle attachment (or using a hand mixer) mix the butter and sugar together on medium speed for approximately 2 minutes. Add in the oil, almond flour, cornstarch, baking soda, baking powder, and salt. Continue mixing for an additional minute until smooth and combined. Add vinegar, vanilla, and almond extracts and mix again until smooth and creamy, scraping down the sides of the bowl as necessary to mix the batter evenly.
Turn the mixer to low speed. In alternating steps add the flour and water, beginning with the flour. Continue mixing an additional 30 seconds, until combined and smooth.
Pour half the batter into each of the prepared pans.
Bake for 30 to 33 minutes, until the edges are golden brown and the center of the cake is set. Insert a toothpick in the center should come out clean.
If using a 9x13 cake pan, bake for approximately 40 to 45 minutes.
Remove cakes from the oven and allow them to cool for 10 minutes. Then invert the cakes onto wire racks and cool completely before frosting.
This cake is divided into 12 slices. The nutrition estimation is based on one serving without frosting.