STEP 1 Ask a grown-up helper to turn the oven on to 180C/160C fan/gas 4. Put a paper case in hole of a 12-hole bun tin.
STEP 2 Put the sugar and butter (it must be soft or you won’t be able to mix it properly) in a bowl and mix it together. Sift in the flour.
STEP 3 Break the eggs into a separate bowl (spoon out any bits of shell that fall in) and add them to the bowl with the vanilla. Mix everything together.
STEP 4 Divide between the cases using a spoon, scraping it off with a knife. Ask a grown-up helper to put the tray in the oven for 20 minutes.
STEP 5 Mix the butter and icing sugar to make a creamy icing. Add colouring, if you like. Push an icing nozzle into an icing bag, then scoop in the icing.
STEP 6Let the cakes cool completely in the tray. Pipe icing onto each cake and decorate with marshmallows or sprinkles, or whatever you like.
