- Preheat oven to 180°C and cut greaseproof paper to fit a big baking tray, and grease the paper.
- Using a food mixer, cream butter and sugars together until light and fluffy.
- Beat in egg and vanilla essence In a separate bowl, sift together flour, baking powder and salt.
- Fold flour into the creamed mixture. Stir in Smarties and bring the mixture together in a ball, using hands.
- Form little balls, using a heaped teaspoon of the mixture, then flatten into a biscuit shape. Try to ensure that the smarties are inside the dough, rather than on the outside of the biscuit.
- Place on baking tray about 5 cm apart. Bake for 10 to 13 minutes until edges are lightly browned and centres are still soft.
- Cool for one minute on the cookie sheet and then cool on wire racks.