Preheat the oven to 170 degrees Celsius. Prepare a 2 lb loaf tin by lining with a loaf tin liner.
Put the butter and caster sugar in a large mixing bowl. Beat with a wooden spoon until light and fluffy.
Crack the eggs in one at a time, beating after each one to fully combine.
Add the flour. Fold in gently. Add the chocolate chips and food colouring and continue to fold until well mixed.
Spoon the mixture into the loaf tin. Smooth the top gently then transfer to the oven for 45 minutes - 1 hour. To check when the cake is done, insert a skewer into the centre. If it comes out clean, it is cooked. If it is coated in batter, cook for 10 more minutes then try again.
When the cake is cooked, remove from the oven and allow to cool.
Mix the icing sugar with 1-2 tablespoons of water. Stir to create a thick paste. If it is too loose, add more icing sugar.
Spread the icing over the top of the cake. Sprinkle over the hundreds and thousands. Allow the icing to set before slicing and serving.