First: I'd give the rock-sugar/lavender mixture the skip at the end, and just sprinkle a little raw sugar on top instead. There is really just the right amount of lavender flavor in these cakes, and I think that mixture would tip them over the edge and into "eating-a-candle-status". Not good.
Second: If you're feeling daring, I recommend topping this cake with a scoop of vanilla ice cream, a drizzle of olive oil, and a sprinkling of sea salt. That's the joint!!
EAT THESE WITH THAT. The extra fat of the olive oil along with the salt, combining with the creaminess of the ice cream, the tartness of the lemon, and the subtle aromatic lavender flavor is... pretty much perfect.