Sugar, and the patience it asks for
A seven tier cake is roughly six weeks of work, and most of that is not baking. It is drawing, then redrawing. Cutting two hundred butterflies by hand and accepting that a dozen of them will break. Piping an arch freehand and starting again when the pressure wavers.
Krishma takes a limited number of weddings a year, which is a commercial decision she keeps refusing to change. A cake she has not drawn, piped and carried in herself is not one she is willing to put her name on.