Center a rack in the oven and preheat to 350 (F). Prepare three 8-inch round cake pans by spraying generously with cooking spray, and lining the bottom of each tin with a parchment paper circle. Spray the parchment circle as well.
In a small bowl, combine 2 cups granulated sugar and the fresh zest from 1 medium orange. Use you fingers to rub the orange zest into the sugar until it is fully distributed throughout the sugar and the mixture becomes fragrant — this will help release oils from the orange peel that will make your cake more flavorful. Set aside.
In a medium bowl, whisk together 3 cups cake flour, 1 tablespoon natural unsweetened cocoa powder, 1 teaspoon baking powder, and 1 teaspoon kosher salt until well combined. Set aside.
In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine 1/2 cup unsalted butter and the sugar from the 2nd step and beat on medium speed until light and fluffy, about 2 minutes. While the butter and sugar are creaming, combine 1/2 cup vegetable oil, 2 tablespoons red food coloring, and 1 tablespoon pure vanilla extract in a liquid measuring cup, using a fork or small whisk to briefly whisk together the ingredients. Lower the mixer speed to its slowest setting and stream into the oil mixture into the butter and sugar, making sure to stream the mixture down the sides of the bowl to avoid making a mess. Once the oil has been added, turn the mixer speed up to medium and continue beating for another 5 minutes, until the mixture is very light and fluffy and a vibrant pinkish color. Once the mixture is light and fluffy, reduce the mixer speed back down to its lowest setting. Add 3 large eggs, one at a time, only adding the next egg when the previous one has fully incorporated. Be sure to use a rubber spatula to scrape down the sides of the bowl after each addition.
Once the eggs have been added, add the flour mixture from the 3rd step in three parts, alternating with 1 1/2 cups buttermilk in two parts, starting and ending with both the flour mixture. Continue mixing until the last of the flour is just incorporated — at this point, it's okay to have one or two flour streaks left in the batter.
In a small ramekin, combine 2 teaspoons distilled white vinegar with 1 teaspoon vinegar. The mixture will begin to bubble and fizz immediately. Quickly add it to the cake batter and mix for an additional minute or so.
Divide the batter evenly among the prepared pans, and bake in the preheated oven for 30 to 35 minutes, or until a wooden skewer inserted in the center of each cake comes out clean and the tops of each cake bounce back when gently poked. Allow the cakes to cool in their pans on a wire rack for about 20 minutes, before turning out of the pans to cool completely.