Preheat oven to 350 degrees. Lightly coat a jelly roll pan (15x10x1-inch) with nonstick cooking spray and then parchment paper that slightly hangs over the edges.

In a large bowl whisk together the cake mix, eggs, water, and oil, until fully incorporated and smooth. Poor into pan, making sure it’s evenly distributed. Bake for about 11 minutes, until cake springs back when lightly touched.

Lay a clean kitchen towel on a flat surface. Sprinkle with the powdered sugar. Gently turn the cake out onto the towel and very carefully remove the parchment paper. While still hot, roll the cake up in the towel, starting at the short end. Cool completely on a wire rack, while rolled up, about an hour.

In the meantime, make the frosting. Place the butter, heavy cream, powdered sugar, and peppermint bark in a large bowl and beat with an electric mixer until smooth and creamy.

Once cake has cooled, unroll the cake carefully. Spread the frosting evenly over the cake. Re-roll the cake.

Make the chocolate ganache: place the chocolate morsels and whipping cream in a medium-sized microwave safe bowl. Microwave for 1 minute until melted. Whisk until combined; whisk in the powdered sugar until combined. Add milk one tablespoon at a time until pouring consistency is reached.

Trim the ends of the cake for a clean look. Transfer to a serving plate, or a cooling rack with a cookie sheet underneath (for a cleaner finish), and pour ganache evenly over the top. Sprinkle with chopped chocolate peppermint bark. Slice and serve!