Preheat your oven to 325°F (163°C) and prepare a ¼ sheet pan with parchment paper and cooking spray.

Sift together the all-purpose flour, baking powder, baking soda, salt, chocolate instant pudding mix, cocoa powder, sugar, and brown sugar in a large bowl.

Whisk together the eggs, buttermilk, brewed coffee, vegetable oil, dark corn syrup, and vanilla extract in another bowl.

Melt the salted butter and semi-sweet chocolate chips together until smooth, then let cool slightly before adding to the wet mixture.

Combine the wet mixture with the dry mixture, mixing gently until just combined to avoid overmixing.

Pour the batter into the prepared sheet pan and bake for approximately 22-26 minutes, until a toothpick comes out clean.

Allow the cake to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.

Heat heavy cream in a saucepan until bubbling, then stir in semi-sweet chocolate chips until smooth. Mix in the peppermint extract and let cool.

Beat cream cheese and butter together, then gradually add powdered sugar and peppermint extract until fluffy.

Slice the cake into layers, frosting between layers with buttercream and adding ganache before stacking. Decorate with ganache and crushed candy canes.