Butter two 20cm loose-bottomed round cake tins and line with baking parchment. Heat the oven to 180C/160C fan/gas 4. Beat the butter and sugar together in a large bowl using an electric whisk until light and fluffy, about 2 mins.

Mix the yogurt, oil, vanilla and eggs together in a jug. Add the flour and wet ingredients to the butter mixture, along with a pinch of salt. Mix everything for 1-2 mins until smooth and creamy.

Divide the batter between the tins and level the surfaces with a spatula. Bake for 25 mins, or until a skewer inserted into the centres comes out clean. If there is any wet mixture, return the sponges to the oven for another 5 mins, then check again. Leave to cool in the tins for 15 mins, then turn out onto a wire rack to cool completely. Once cooled, the sponges will keep in an airtight tin for five days or wrapped well and frozen for three months.

Next, make the buttercream. Beat the butter, sugar, milk and vanilla in a large bowl using an electric whisk, or in a stand mixer until smooth and creamy, about 3 mins.

Use a large tray, board or cake stand to assemble the cake. Cut the cooled cakes in half with a large bread knife to make four semi- circles. Using a 10cm biscuit cutter, stamp out a smaller semi-circle from one of the pieces and set aside. The cake offcuts can be saved for a trifle or frozen for up to three months.

Spread 2-3 tbsp buttercream over the base of the board. Use another 2-3 tbsp layered with 2 tbsp jam to sandwich two of the large semi-circles together. Put the sandwiched cakes curved-side up on the board. Spread 2-3 tbsp buttercream and 2 tbsp jam over one of the remaining large semi-circles and press this onto the cakes on the board to make a domed three-layer cake. Finally, stick the smaller cut-out semi-circle on one side using a little more buttercream and jam to make the entrance to the igloo. Chill for 30 mins. Meanwhile, roll out a piece of black fondant to 6cm in diameter and cut into two semi-circles.

Cover the entire cake with buttercream, using a palette knife to smooth it over the surface and cover any gaps. Don’t worry about being too neat, as any imperfections will be covered. Press one of the black semi-circles of fondant onto the front of the small cake to mark out the entrance of the igloo. Press the coconut all over the rest of the cake.

Use 100g of the white fondant to make snowballs in various sizes and arrange them around the base.

To make the penguins, divide the remaining black fondant icing into four pieces of different sizes. Roll each piece into an egg shape, and pinch out little flippers on each side. Press out a disc of white fondant for each penguin’s belly, and attach with a dab of water. Make eyes by sticking little black spots onto small white discs of fondant and attach to the penguins. Finally, make orange triangle beaks and flippers and stick these on. Put the penguin family around the cake. Will keep in an airtight tin for up to five days.