Cream the butter and sugar until light and fluffy.
Grate in the zest from the oranges - ensuring ½ of one is left for the buttercream - and cream some more.
Beat in the eggs, one by one, adding a little of the flour to prevent curdling if necessary.
Sift in the flour, baking powder and soda and stir gently to combine.
Squeeze in the orange juice (you may not need all of it, and stir gently again until combined. You are looking for a softish dropping consistency and may not need all of the juice
Divide the mixture between 48 mini silicone muffin moulds or tins lined with cases. You may need to do this in batches if you don't have enough moulds - I did it in two.
Bake in the middle of the oven at 180℃ for 15-20 minutes until the cakes are well risen and firm to the touch.
Allow to cool in the moulds for a couple of minutes, then turn out onto a rack to cool.
Cream the butter and icing sugar together well until light and fluffy.
Beat in the remaining orange zest.
Add a little of the remaining orange juice and beat well, followed by a bit more. You don't want to curdle the mixture, so be careful.
Beat in the food colouring if you are using it, one drop at a time until you have the colour you are looking for.
Spoon or pipe the mixture onto the cooled cakes and decorate with sprinkles or a little glitter if desired.
Will make 24 regular sized cupcakes, although the recipe can easily be halved to produce 24 mini cakes or 12 regular sized ones.Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.