You will need about 12-15 butterflies and about 100 blossoms in three sizes (I made 25 tiny 1/4-inch blossoms, 25 medium 1/2-inch blossoms and 50 large 5/8-inch blossoms).
The decorations are applied randomly, so this is just a guide. Knead some of the fondant left over from covering the cakes and drums until pliable, and roll out thinly (no more than 1/8-inch thick) on a board sprinkled with a little confectioners' sugar. Stamp out the blossoms and butterflies and allow to dry for a few hours, preferably overnight. I lay them out as I make them in boxes interleaved with parchment paper. Prop up the butterflies' wings between two sticks (you could use spare dowels), so the wings will dry as if in flight.
If you like, pipe the centers of the blossoms with a tiny dot of royal icing and then press on a gold dragee. If you prefer, just pipe a dot for the centers. Once the butterflies are dry, paint the edges of the wings with egg white and dip into the glitter.
To finish the cake, apply the ribbons by sticking them at the back of each cake using a little royal icing. On the middle tier, overlay the wide organza ribbon with two bands of narrow gold ribbon. Wrap the base drum with the double-sided sticky tape, then stick on its ribbon.
Casual, informal designs do have one huge advantage: any blemishes or marks in the icing can be covered by a decoration! Randomly apply the butterflies and little blossoms all over the three-tiered cake, sticking on with the royal icing. As a final touch, place the two doves in the center of the top tier.
View more luxury wedding cakes and other baked goods on Fiona Cairns' website. Her first cookbook, "Bake and Decorate," was released in March.