One image showed Lilibet's two-tier birthday cake, decorated with an Ariel theme from The Little Mermaid.In another clip, Lili and her brother Archie, six, were seen meeting Elsa from Frozen.

To make it, you'll need just two large sweet potatoes, cut into small cubes, and 200g of dark chocolate. If you're feeling fancy, you can also whip up a topping using 100g of dark chocolate and ...