Preheat & Prep. To start, preheat oven temperature to 350 degrees F. Lightly grease an 8-inch cake pan and line with parchment paper. (Don't skip the parchment!)

Melt Chocolate & Butter. In a large microwave-safe bowl, combine butter and 8 ounces chocolate. Gently melt on low power in 10-15 second intervals, stirring in between each interval, until this mixture is smooth and glossy. (Alternatively, you can do this in a double boiler on the stovetop.)

Combine. Add sugar, vanilla, peppermint extract, and salt to chocolate mixture and stir to combine. Add eggs one at a time, beating to fully incorporate each egg before adding the next one. Next, add the cocoa powder and stir until just combined and no large clumps remain.

Transfer the batter to your prepared pan and gently smooth the surface into an even layer.

Bake in preheated oven 40-45 minutes, or until a toothpick inserted in the center of the cake comes out clean with just a few moist crumbs. The top of the cake should spring back when gently pressed and the interior temperature should be between 195-200 degrees F.

Cool in the pan 10-15 minutes, then carefully turn the cake out onto a wire rack to cool completely. Allow the cake to fully cool before making the chocolate ganache.

Heat the cream in a large microwave safe bowl until it's just steaming. Do not let the cream boil or simmer, just heat it to steaming. Add the peppermint extract and stir to combine.

Mix In Chocolate. Add 6-ounces chocolate and stir until the chocolate is melted and the ganache is smooth and glossy. (If your chocolate ganache seems too thick, you can mix in additional cream 1 teaspoon at a time until it's a pourable consistency.)

Decorate. Transfer the cake to your desired serving plate or cake stand. Pour the ganache onto the cooled cake and gently smooth into an even layer with an offset spatula. Let the ganache set completely, then sprinkle with candy cane or garnish with chocolate curls right before serving. Cut into slices & enjoy!

Store leftover cake covered in the refrigerator 3-4 days, or freeze up to 2 months. This cake is best served at room temperature, so pull leftover cake out of the fridge to come up to room temperature before serving again.