Preheat the oven to 350°F (180°C). Prepare two 8-inch* (see notes) cake pans by spraying with non-stick spray and lining the bottoms with circles of parchment paper.
Sift the all purpose flour into a mixing bowl and add the sugar, baking soda and salt and mix in.
Add soy milk, oil, vinegar, vanilla extract, orange extract and orange zest and mix it into a batter. Don't overmix.
Divide the batter between the two prepared cake pans and bake for 30 minutes or until a toothpick inserted into the center of one of the cakes comes out clean.
Let the cakes cool for a few minutes in the pans before removing them from the cake pans and placing on a wire cooling rack to cool completely before frosting.
Prepare your frosting by adding the powdered sugar, vegan butter, salt and orange extract to the bowl of a stand mixer and starting at slow speed, gradually increase speed until the frosting is thick and smooth.
When the cakes are cooled frost the cake and decorate with orange zest and orange slices around the sides (optional).