Use a serrated knife to level each cake layer, removing the domed top so you get nicely even, level layers.
If you baked 8-inch cakes like me, you'll need to use a serrated knife to split each layer in two (so you end up with 4 thin layers).
Take one layer of cake and place it onto a serving plate. Brush the layer with some of the lemon syrup (leftover from making the candied lemons) and then top with 1/4 of the buttercream, spreading it out into an even layer. Repeat the layering of cake, lemon syrup, buttercream until you've stacked up all the cake layers and frosted the top.
Stir together the glaze ingredients until a thick, pourable glaze is achieved. Pour it all over the top of the cake, coaxing it to the edges so that it drips down the sides.
While the glaze is still wet decorate the cake with the candied lemon slices and pearl sugar.