Preheat oven to 350°F and line jelly roll pan with parchment paper
Whisk together flour, cocoa powder, baking powder, and salt
Beat eggs and sugar on high for 5 minutes until thick and pale
Fold in vanilla, buttermilk, vinegar, and red food coloring
Gently fold in dry ingredients until just combined
Spread batter evenly in pan and bake 10-12 minutes
Flip warm cake onto powdered sugar-dusted towel, peel off parchment
Roll cake with towel inside while warm and let cool 30 minutes
Beat butter until fluffy, gradually add powdered sugar
Mix in cream, peppermint extract, and salt until smooth
Unroll cake, spread buttercream evenly, leaving 1/2-inch border
Re-roll cake without towel, place seam-side down
Frost outside if desired, top with crushed candy canes
Refrigerate 30 minutes before slicing and serving