5 Things I Learned Making a Unicorn Cake

I shaped my fondant horn an hour before decorating and it slowly leaned over like a sad candle, so learn from me: fondant needs a full 24 hours to dry. Knead half a teaspoon of tylose (CMC) powder into 150 g of white fondant, roll two 30 cm ropes, twist them together around a wooden skewer and taper the tip. Stand it upright in a mug or press it into a foam block so it dries straight, and lay the two teardrop-shaped ears flat with a little pink dust brushed inside. The next day, paint the horn with edible gold lustre dust mixed with a few drops of clear alcohol or lemon extract. If the party is tomorrow and you have nothing dried, a shop-bought unicorn topper set costs under 10 pounds and nobody will judge you.

My first attempt at frosting a barely cooled sponge dragged crumbs through the white buttercream and I nearly cried. Now I wrap each cooled 18 cm layer tightly in cling film and freeze them for at least an hour; cold cake is firmer, sheds almost no crumbs and is far easier to level with a serrated knife. You can bake the layers up to two months ahead this way, which turns a scary all-day project into a relaxed two-day one. Stack the layers straight from the freezer, apply a thin crumb coat, then chill the whole cake for 30 minutes before the final coat. Every stage of a unicorn cake goes better when the cake underneath is cold.

My first batch of buttercream was lovely on toast and useless for a mane; the rosettes slumped and slid within ten minutes. The ratio that finally worked is 400 g of softened butter to 800 g of icing sugar with only 2 to 3 tablespoons of milk, beaten until just smooth. Always tint it with gel colours, never liquid ones, because liquid colouring thins the buttercream back into slump territory. Test it by piping one rosette onto baking paper: the ridges should hold sharp edges without drooping. If your kitchen is warm, pop the filled piping bag in the fridge for 10 minutes between colours and it will behave again.

I originally piped rosettes randomly all over the top and it looked like a confetti explosion, so I scraped it off and started again with a plan. Place the horn and ears first, then pipe your biggest Wilton 1M rosettes around the base of the horn and let them cascade over the top edge and down the back of the cake in a gentle S-curve. Fill the gaps with smaller stars from a Wilton 21 or 32 tip and a few dots from a round tip, alternating colours so no two matching shades sit side by side. Practise every new swirl on baking paper first, because buttercream scrapes straight back into the bag and costs you nothing. The moment the mane followed one flowing line instead of exploding everywhere, the whole cake suddenly looked professional.

Black buttercream needs an alarming amount of gel colour, tastes bitter and turned my test batch grey-purple, so I switched to melted dark chocolate and never looked back. Snip a tiny hole in a piping bag (or use a number 2 or 3 round tip) and draw each closed eye as one gentle downward curve with three short lashes flicking out from the end. Practise the shape a few times on baking paper, because the eyes are the one part of a unicorn cake everyone actually stares at. Place them lower on the front than feels natural and space them wide, roughly 7 to 8 cm apart on an 18 cm cake, or your unicorn looks cross-eyed. If you botch one, chill the cake for 10 minutes and the set chocolate lifts off cleanly with a toothpick.

Treat it as a two-day project: horn, ears and cake layers on day one, buttercream and decorating on day two, and it stays genuinely fun instead of frantic. The whole homemade unicorn cake cost me about 18 pounds in ingredients versus the 60 to 80 pounds our local bakery quoted, and the birthday girl liked mine more because she chose the mane colours. You only truly need one 1M piping tip; everything else is a bonus. Chill the cake at every stage, keep the finished cake in the fridge, and take it out 2 to 3 hours before the party so the sponge softens back up. And honestly, wonky rosettes read as charming, not failed; not one six-year-old inspected my seams.