Cream the butter and sugar in a bowl with an electric mixer until pale and fluffy. Add the vanilla extract, eggs and salt and mix until combined. Add the milk. Add the flour and baking powder and mix until well combined. Divide the batter into 2 bowls and dye one bowl any colour that you like!

Pour the batter into 2 greased 9-inch round cake pans and bake at 350F for 35-40 minutes, until a skewer inserted into the middle of the cakes comes out clean. Cool completely.

Cream the butter in a bowl with an electric mixer until pale and fluffy. Add the vanilla extract and combine. Add the confectioner’s sugar one cup at a time until fully combined, then beat for 3-4 more minutes until fluffy.

Slice the top off of both cakes to smooth the surface. Slice both cakes in half and stack them on top of each other, alternating the colours and spreading buttercream between each layer.

Slice the crusts off the cakes to create clean edges and place the cake in the fridge for 15-20 minutes, to chill.

Coat the cake in a thin layer of buttercream and return the cake to the fridge until the buttercream stiffens, about 10-15 minutes. Coat the cake in a second, thicker layer of buttercream and return it to the fridge while you make the mirror glaze.

Sprinkle the gelatin into the ½ cup + 1 tbsp water. Let sit for 5 minutes as the gelatin develops. Add this to the white candy melts and condensed milk and roughly mix to combine.

In a small pot, combine the glucose, sugar and 2/3 cup water. Set to medium heat and stir until the sugar dissolves. Attach a candy thermometer to the pot and cook until the mixture reaches 217F. Pour onto the candy melt mixture and whisk until everything has melted and combined. Add the white food colouring and stir to combine.

Place about ¼ cup of glaze into 6 bowls and dye them the colours of the rainbow. Allow the rainbow glazes and white glaze to come to room temperature – this is VERY important!! You’ll see what happens when you pour it while it’s warm in the video!

Transfer the cake to a wire rack with a cookie sheet underneath. Gently pour the white glaze onto the cake. Drizzle the rainbow glaze on top in the order of the rainbow. Use an offset spatula to gently smooth the surface and blend the colours. Return the cake to the fridge until set, about 15 minutes. Serve and enjoy!