Preheat your oven to 160°C. Grease and line an 8x10 inch tin with parchment paper. For the base, whisk the sugar, oil, honey, eggs and buttermilk together in a freestanding mixer until just combined.
Gently mix through the remaining ingredients (flour, baking powder, bicarbonate of soda and funfetti).
Pour the mix into the prepared tin and bake until it’s golden and springs back (about 40 minutes).
To make the buttercream mix the honey in a small saucepan fitted with a sugar thermometer. Bring to the boil, then simmer until it reaches 110°C. Pop your egg whites in the bowl of a freestanding mixer and whisk into soft peaks. Now, bring the honey to 121°C, with the mixer running, pour into the whipped whites in a steady stream, easy does it!
Adding a tiny bit of butter at a time, continue to whisk at a slightly lower speed until it is all fully incorporated.
Continue to whisk until it has cooled (when you feel the bowl is the same temperature as your hands).
Spread the buttercream icing across the cooled cake, drizzle with honey and sprinkle with extra funfetti.