Supermarket party cakes are undeniably ultra-processed, but some offer better taste and fewer additives than others. A recent taste test evaluated nine cakes from major UK supermarkets, scoring them on appearance, taste, texture, value, certifications, animal welfare, and sugar content. The results highlight significant differences in quality and ingredient transparency.
Waitrose Over the Rainbow Cake Takes Top Spot
The Waitrose Over the Rainbow cake (£18 for 1.28kg, serves 16) was rated the best overall, earning four out of five stars. It features a deep, 15cm-diameter, 9cm-high layered sponge in light purple, orange, and yellow, covered in sprinkles with piped icing. The vanilla buttercream contains real vanilla extract, and the sponge is soft and moist. Despite tasting sweet, it has 39.2% total sugars—lower than most competitors. However, it contains eight additives, including four emulsifiers and glucose-fructose syrup. It is made with free-range eggs, unsalted butter, and is palm oil-free.
Best Bargain: Asda Rainbow Jazzie Cake
The Bakery at Asda Rainbow Jazzie cake (£15 for 1.3kg, serves 20) was named the best bargain. It scored two out of five stars, described as a huge cake with magenta, yellow, and carrot-coloured layers. The sponge is fluffy and moist, but the icing is greasy, flavourless, and bland—though kid-friendly. It has only six additives (including palm oil and carminic acid from cochineal) and the lowest total sugars at 33%. Notably, it is not suitable for vegetarians.
Other Cakes in the Test
M&S Rainbow Layer Cake (£20 for 900g, serves 8) earned four stars for its tall, pastel-coloured sponge with silky Madagascan vanilla buttercream. It has 41.6% sugars and only five additives, with no palm oil, preservatives, or glucose-fructose syrup, making it the best splurge option.
Lola’s Vanilla Layer Cake (£27.50 for 660g, serves 8) received three stars. It is elegant with a delicate buttercream and multicoloured pearl sprinkles, plus a tart compote centre. However, it contains 12 additives, including palm oil, titanium dioxide (banned in the EU since 2022), and propylene glycol, with 43.4% sugars.
Fiona Cairns Mini Pink Boutique Cake (£9 for 290g, serves 4) scored three stars. It is a moist sponge sandwich with thick icing, vanilla buttercream, and raspberry jam. Despite using butter and free-range eggs, it has 10 additives and the highest sugar content at 44%.
Sainsbury’s Taste the Difference Rainbow Layer Cake (£18.50 for 685g, serves 10) earned three stars. It is a tall, 14cm-diameter cake with pink, yellow, carrot, and deep-purple layers, moist sponge, and balanced vanilla icing. It has 42.1% sugars and six additives, including palm oil and palm stearin.
Lidl Rowan Hill Bakery Madeira Party Cake (£4.79 for 888g, serves 16) scored two stars. This large Victoria sandwich with jam filling contains eight additives, including emulsifiers, glucose-fructose syrup, and palm oil, with 40.3% sugars.
Tesco Vanilla Party Cake (£10 for 976g, serves 16) also scored two stars. It is a classic Victoria sponge with raspberry jam, bland icing, and 10 additives, including three emulsifiers, glucose-fructose syrup, and two palm products, with 42.4% sugars.
Morrisons Sprinkle Cake (£15 for 1.425kg, serves 20) received two stars. It is a four-layer sponge with apple and raspberry jam, covered in fondant-like icing. It contains nine additives, including emulsifiers, glucose-fructose syrup, and palm oil, with 42.5% sugars.
Aldi Village Bakery Party Cupcake Platter (£4.49 for 12 cupcakes) was the worst, earning one star. The cupcakes have soft, moist sponge but synthetic, gummy icing. They contain 10 additives, including palm oil and palm fat, with 41.6% sugars.
Key Takeaways
The test found that price does not always correlate with lower processing levels. Even premium cakes contained multiple emulsifiers, preservatives, and glucose-fructose syrup. Total sugar content varied widely, from 33% in Asda's cake to 44% in Fiona Cairns. Additives ranged from five in M&S to 12 in Lola’s. Consumers are advised to check labels for additives and sugar content, even in higher-priced options.
