Heat the oven to 180 C/160 Fan/gas 4 and line 12 holes of a muffin tin with paper cases. Whisk the oil with the sugar and eggs, then stir in the plain yogurt and lemon juice.

Mix the flour with the baking powder, a pinch of salt and the custard powder, and add this to the wet ingredients. Mix well and add the 2 tbsp of sprinkles, if you like. Use an ice cream scoop or two teaspoons to divide the mixture between the muffin cases. Bake the muffins for about 25 mins until golden brown, then let them cool completely.

For the frosting, beat the butter with the icing sugar and vanilla extract for about 5 mins until the colour is slightly lighter and the texture is creamy. Beat the soft cheese to loosen, then stir it in.

Put the frosting in a piping bag with your choice of nozzle and pipe icing onto each muffin. Decorate with the sprinkles. Will keep chilled for up to three days.