Preparation

● Preheat the oven to 350 degrees. Spray a 10-by-15-inch jellyroll pan or a sheet pan with nonstick spray and line with parchment paper.
● In a large mixing bowl, whisk together the cake flour, cocoa powder and salt. Set aside. and salt in a bowl.
● In the bowl of a stand mixer, beat together the vegetable oil and sugar on medium speed until well blended, then beat in the egg. With machine on low speed, slowly add red food coloring and vanilla until mixed.
● Add half the flour mixture, then half the buttermilk until mixed thoroughly. Add the remaining flour mixture and buttermilk, scraping down the bowl until combined. Turn off machine.
● Place the baking soda in a small dish and stir in the vinegar. Add the mixture to the batter with the machine running on low until combined.
● Pour the batter into the prepared pan and spread evenly. Bake 15 to 20 minutes, until puffed. The cake should bounce back when you lightly press the top.
● Spread a clean kitchen towel on the counter and dust with powdered sugar. Flip the hot pan over to turn the cake out onto the towel. Remove the parchment paper. Dust the cake with more powdered sugar, then use the towel to carefully roll the hot cake into a spiral starting from the short side. Let cool wrapped in the towel, about 1 hour.
● Meanwhile, in the bowl of a standing mixer, beat together the butter, cream cheese, remaining 2 cups powdered sugar, milk and peppermint extract until combined. Set frosting aside.
● Carefully unroll the cake and spread with a ½-inch thick layer of frosting. Carefully roll the cake up again and gently move to a serving plate. Spread the remainder of the frosting all over the top of the cake, covering any cracks that may appear. Garnish with crushed peppermint candy.