Preheat your oven to 180°C (160°C for fan assisted ovens) / Gas Mark 4. Line a muffin tin with the cupcake cases that come in the pack.
Mix the eggs, oil, water and the Vanilla Cupcake Mix gently together and whisk (by hand or electric mixer) for 2-3 minutes until smooth and creamy.
Pour the mixture evenly into the cupcake cases
Bake in the centre of the oven for 16 minutes or until a rounded knife, inserted fully into the centre of a cupcake comes out clean, then cool on a wire rack.
Bake Turn the oven up to 190C, 170C fan, gas 5.
Stir the cookie mix together with the water and mix until you have a stiff dough. Fold through the chocolate sprinkles reserving a few to decorate the cookies once rolled. Roll into grape sized balls and place onto the baking tray, leaving gaps between them. Flatten slightly and gently press in the reserved smarties.
Bake in the centre of the oven for 8-10 minutes until golden. Leave to cool.
Whisk the icing from the pack, with the butter and a little water if necessary, until smooth. Spoon into a piping bag with a star nozzle and pipe onto the cupcakes. Top with the cookies and sprinkles.