Preheat the oven to 350°F/177ºC. Prepare three 6-inch or two 8-inch cake pans by spraying the sides with cooking spray and fitting a parchment paper circle to the bottom of the pan.
Finely chop the maraschino cherries and place them into a fine mesh sieve set over a bowl. This will help drain some of the excess juices while you continue on in the recipe.
In a liquid measuring cup or jar, mix together the buttermilk and maraschino cherry juice. Set aside.
In a medium bowl, add the sifted cake flour, baking powder, and salt. Whisk together and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter at high speed until creamy, about 2 minutes. Add the sugar and cream it together with the butter at medium-high speed for another 2 minutes. Turn the mixer to low and add the egg whites one at a time, mixing until they are just combined and scraping down the bowl and paddle as needed. Add the vegetable oil and vanilla, increase the mixer speed to high and beat for 1 minute.
Turn the mixer off and add the flour mixture all at once. Mix the ingredients on low speed until just combined, then slowly pour in the buttermilk-cherry juice mixture. Continue mixing at low speed for about 30 seconds, until the batter is uniform and combined.
Add 2 teaspoons of flour onto the chopped maraschino cherries and toss them to coat. Gently fold them into the batter using a rubber spatula. Then, divide the batter evenly between the prepared cake pans and bake for 30 to 35 minutes. They’re done when they spring back to the touch and a toothpick inserted into the centers comes out clean or with just a few moist crumbs on it. Let the cakes cool in their pans for 5 minutes, then remove them from the pans and allow them to cool completely on a wire rack