Preheat oven to 170 C / Gas 3. Grease and flour two 20cm (8 in) cake tins.
Sift all dry ingredients into a bowl and set aside.
Place eggs in a mixer bowl. Using the whisk attachment of your electric mixer beat until it forms ribbons, about 4 to 5 minutes.
While eggs are whisking place milk and butter in a pan and gently warm till butter has melted.
Add caster sugar to eggs and beat for another 4 minutes.
Fold in the vanilla extract. Add all dry ingredients to mix and mix on slow till well combined.
Pour in the butter and milk mixture and on slow till combined.
Pour mixture as equally as you can into the prepared tins. Bake until golden, 25 to 30 minutes.
After baking, leave in tins for 10 to 15 minutes to cool before unmoulding on rack lined with baking parchment. Cool for 2 to 3 hours.
Cut each cake in half, reserving the crumbs. Fill both cakes with a layer of buttercream. Spread the top of one cake with buttercream and place the other cake on top. Using the crumbs from cutting the cakes, coat the cake with crumbs all over. Place into the fridge to set.
Cut the sugar bracelets and place the sweets in a bowl. Take the 2 wires and curl the ends of each. Then leaving 5cm (2 in) of wire, twist the rest of the wire together and spread top of wires apart to make antennas for butterfly. Thread the sweets onto the wire and set aside.
Take cake out of fridge and cut in half vertically. Then at about two thirds way down at a 45 degree angle cut halves into half to make butterfly wing and body.
Cover each section with buttercream. Place the cake on a board and use icing sugar to decorate the cake in different colors for each segment as shown in the photo. Using the wire, measure the length you need for the body and place it in the centre of the butterfly. Trim the wire and turn under the last sweet to secure. Dot icing on a white fondant board for extra effect.