Preheat the oven to 180C/350F and grease and line three 8 inch round cake tins. I spray the pans with Wilton Bake Easy and then line the bottoms with greaseproof paper.
Place the butter/marg and sugar into a large bowl, or the bowl of your stand mixer, and beat on medium-high speed until light and fluffy. This will take around 2 minutes.
Add in the eggs and peppermint extract and, scraping down the sides as necessary, mix on medium-high speed until well incorporated and smooth.
Add in the flour, baking powder and salt, if using, and mix until the mixture starts to come together. Then add in the milk and continue to mix on low-medium until the mixture is smooth and well combined.
Divide the batter between the three cake tins evenly. I use a 1/2 cup measuring cup to divide my mixture between the tins.
Place in the oven for 20-25 minutes, until risen, lightly golden and an inserted skewer into the centre comes out clean.
Leave to cool in the pans completely. At this stage you can wrap the cake layers individually in cling film and leave overnight before decorating.
To make the frosting: Place the butter, icing sugar and peppermint extract into the bowl of your stand mixer and begin mixing on low until the icing sugar starts to combine with the butter. Then turn the speed up to high and beat until light and fluffy.
Add in milk 1/2 tbsp at a time, mixing in between each addition, until you have a light frosting that is easily spreadable, but still holds its shape.
Add in the Wilton icing whitener, if using and mix on high until completely combined.
Place a small blob of frosting into the centre of a cake plate/plate.
Place one of your cake layers top side up in the centre of the plate. Spoon around ¼ cup frosting into the centre of the cake and spread out with a small angled spatula. Cover the whole of the top of the cake.
Sprinkle with crushed candy canes if desired (I didn’t have enough candy canes to do this step!)
Place the next cake layer, top side up, on top of the frosted cake. Spoon ¼ cup frosting onto the top of the cake and spread out until even. Sprinkle candy canes over the frosting.
Place the final cake layer bottom side up, on top of the frosted cake. Spoon the remaining frosting into the centre of the cake and use a small angled spatula to spread the frosting over the top and down around the side of the cake.
Using an icing turntable will make icing the sides much easier. Just be very delicate and try not to press too hard with the icing. Push it gently into gaps and smooth it over until the entire cake is covered. For the top, I would advise using a small angled spatula. For the sides, you can use a large straight spatula, but I actually prefer to use the same small angled one as it allows you to be very precise with icing the bottom of the cake. I normally ice with one hand; using my left hand to turn the turntable and spin the cake.
Once the whole cake is iced; fill a jug with warm water and dip the spatula into the water. Shake it off and then use the warm spatula to run very gently over the top and sides of the cake, smoothing out the icing as much as you can. Keep warming the spatula every 10 seconds or so, to make sure your icing ends up as smooth as you can possibly make it!
To decorate: Press the remaining crushed candy canes all around the bottom of the cake to create a border. Mine was around 1 inch high.
Press whole candy canes into the top of the cake; I put larger ones in the middle, mini ones around the outside and medium sized ones in the middle. I also pushed them in at different heights, but you can decorate however you see fit!
If you have any crushed candy canes left, sprinkle a few on the top of the cake; I just did some around the edges.
Leave to set for 15 minutes and then serve!
Candy Cane Layer Cake will keep covered, at room temperature for 2 days, or in the fridge for 4 days.