Make the cake:

1. Preheat the oven to the temperature listed on the cake mix box. Grease a 13×9-inch baking dish with nonstick spray.
2. In a large mixing bowl, whisk together the dry cake mix and pudding mix.
3. Add milk, melted butter, oil, eggs, vanilla, sour cream, and vinegar. Beat on low speed for 30 seconds, then on medium for 2 minutes until the batter is smooth and thick.
4. Pour the batter evenly into the prepared pan and spread it out with a spatula.
5. Bake according to the box instructions, checking about 5 minutes early since this version is slightly richer and denser.
6. Let the cake cool completely in the pan before frosting.

Make the frosting:

1. In a large bowl, beat the cream cheese and butter together until smooth and creamy (about 2 minutes).
2. Mix in the peppermint and vanilla extracts.
3. Gradually add powdered sugar, 1 cup at a time, beating on low until incorporated. Increase to medium-high speed and whip until light and fluffy.
4. Add heavy cream, 1 tablespoon at a time, until your desired texture is reached.
5. Fold in crushed candy canes for a little sparkle and crunch.

Assemble the cake:

1. Spread the peppermint cream cheese frosting evenly over the cooled cake.
2. Pipe a border and swirls, if desired.
3. Garnish the top with extra crushed candy canes, peppermint bark pieces, peppermint-themed garnishes, and sprinkles.
4. Chill for 20–30 minutes before slicing for clean cuts and a perfect peppermint crunch.