Preheat oven to 350°F (175°C) and grease one 8-inch cake pan.
Sift together cake flour, baking powder, and salt.
In another bowl, whisk cherry juice, egg whites, and buttermilk.
Beat butter and sugar until fluffy, then add oil and vanilla.
Gradually add dry ingredients and wet mixture alternately, mixing gently.
Toss chopped cherries with flour and fold into batter.
Pour batter into the pan and bake for 25–30 minutes or until a toothpick comes out clean.
Cool the cake completely before frosting.
For buttercream, beat butter until creamy, add sugar, cherry juice, and cream, and whip until fluffy.
For ganache, pour hot cream over chocolate and stir until smooth.
Frost the cooled cake, drizzle ganache, and decorate with cherries.