Preheat oven to 350°F (177°C). Position rack in the middle of the oven. Grease and line a 9 x 3 inch deep round cake pan with a circle of parchment. Use cocoa powder instead of flour to coat the sides of the greased cake pan.
In a large bowl whisk together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt until no lumps remain. Set aside.
In the bowl of a stand mixer, using the paddle attachment, cream together the Redpath® Dark Brown Sugar, melted butter, and vegetable oil until combined; 2 minutes. Add in the eggs one at a time, fully incorporating each egg before adding the next one. Mix in the vanilla extract.
In a microwaveable bowl or measuring cup, heat 2/3 cup (160 ml) of the milk until hot. Stir and dissolve the instant espresso into the hot milk.
On low speed, add 1/3 of the dry ingredients into the batter, mixing until just combined. Add in the remaining 2/3 cup (160 ml) milk and mix until combined. Repeat process with the remaining flour and the warm espresso-milk mixture, ending with the dry ingredients; do not overmix.
Pour and evenly smooth out the chocolate batter into the prepared cake pan. Place into the preheated oven. Bake for 55 to 60 minutes or until a skewer inserted into the centre of the cake comes out clean.
Let cake cool slightly in the pan; 10 minutes. Carefully run an offset spatula or a small paring knife around the cake. Invert cake and set right side up to cool completely on a wire cooling rack.
Make the Quick Buttercream as directed. Add the salt when creaming the butter. Mix in the peppermint extract when adding the vanilla extract.
With a sharp, serrated knife, slice off the rounded top of the completely cooled or chilled cake, creating a level surface.
With a steady hand, slice the chocolate cake in half. Carefully remove the top layer.
Transfer some of the peppermint buttercream into a piping bag fitted with a large round piping tip.
Place the bottom layer onto a plate or turntable. Starting from the centre, pipe buttercream in concentric circles onto the cake layer. Pipe a second layer of buttercream over the first layer. Smooth cream with an offset spatula. Place the top layer onto the piped buttercream, gently pressing down.
Spread a thin layer of the peppermint buttercream onto the top and sides of the cake; this is the crumb coat.
Place into fridge to set up; about 15 minutes. Evenly spread the remaining buttercream onto the tops and sides of the cake.
Decorate the sides and top of the cake with the crushed candy canes or peppermint candies.
*The chocolate cake can be made several weeks in advance. Cool cake completely, wrap in two layers of plastic wrap and then in a layer of aluminum foil. Place into the freezer for up to 2 months. Layers can be cut when cake is completely cooled and each layer wrapped individually and frozen or cut after thawing the cake slowly in the fridge overnight.
*A chilled cake is easier to split into layers.
*A dark instant coffee can be used in place of instant espresso.
*For a cake with an even stronger peppermint flavour, add 1/4 to 1/2 teaspoon (1 to 3 ml) of pure peppermint extract when adding the vanilla extract to the chocolate cake batter.