Chocolate peppermint bark cake with peppermint buttercream and chocolate ganache

Set the oven to 350.

Stir 60 grams Dutch processed cocoa powder into one cup of hot coffee in a large bowl and set it aside a few minutes to bloom.

Sift 300 grams all-purpose flour, 300 grams sugar, half a teaspoon baking soda and two and a half teaspoons baking powder together into another large bowl.

Whisk in one teaspoon of kosher salt.

Into the cocoa mixture add 110 grams sour cream, 120 millilitres whole milk and 110 grams brown sugar.

Add 180 millilitres veggie oil and four eggs.

Add one tablespoon of vanilla and whisk until smooth and homogenous.

Spray three eight inch pans and wrap soaked baking strips around them.

Pour the wet into the dry and whisk until almost combined, scraping the bottom for hidden flour without overmixing.

Divide the batter between the pans; a thicker layer should be the bottom layer because it gets compressed anyway.

Bake at 350 for 30 to 35 minutes, until a skewer inserted in the middle comes out clean.

Bring two inches of water to a simmer and set a bowl over the pot.

Chop the white chocolate first, then the dark chocolate, and melt the dark chocolate over the low simmer, stirring occasionally until silky and smooth.

Pour the dark chocolate onto a sheet of parchment and spread it about a quarter to an eighth of an inch thick.

Melt the white chocolate over low heat with a clean spatula, taking the bowl off the heat if it feels too hot, and stop while a couple of little bits are still unmelted so residual heat finishes it.

Crush the candy canes gently in a sheet of paper, keeping the pieces big.

Wait until the dark chocolate is semi-set, the bottom hard and the top still slightly wet and matte at the edge, so the white chocolate bonds instead of mixing or snapping apart.

Spread the white chocolate gently over the dark and sprinkle the crushed peppermint over the top.

Set the bark aside until fully firm, or chill it; it can be made a day ahead.

Cream three sticks of room temperature unsalted butter with three quarters of a teaspoon of salt in a stand mixer with a paddle until smooth.

Add three teaspoons of vanilla and combine.

Mix in the powdered sugar on low in batches, scraping the bowl down occasionally.

Add a third of a cup plus two tablespoons of heavy cream and raise the speed to medium.

Add one and a quarter teaspoons of peppermint extract, scrape the bowl down and beat on medium about three minutes until creamy, fluffy and smooth.

Spread about three quarters of a cup of frosting between each layer and sprinkle a little crushed candy cane over it, keeping the bigger pieces back for the skirt.

Frost the top and sides, letting gravity carry the frosting to the bottom, and smooth the sides with a bench scraper on a turntable; the top only has to be level because ganache covers it.

Press crushed candy cane pieces onto the bottom third of the cake and chill it.

Chop more chocolate, pour cream warmed until steamy over it, set it aside a few minutes then stir until silky smooth.

Pour the ganache onto the chilled cake and level it with a spatula out to the edge, coaxing drips down gently.

Snap or cut the chilled peppermint bark; it is not tempered so it will not snap crisply.

Arrange the bark on top of the cake, which can be removed when serving, and cut.