For the cupcakes
1 cup (2 sticks) sweet butter, softened
1 cup superfine sugar
2 cups self-rising flour
1 tsp. vanilla extract
For the frosting
2 1/2 cups confectioners' sugar
2 tbsp. lemon juice
2 tbsp. gold-colored sugar
2 tbsp. green-colored sugar
2 tbsp. purple-colored sugar
Preheat the oven to 350 degrees F. Place 18 paper baking cups in muffin pans. Combine all the cupcake ingredients in a large bowl and beat with an electric mixer until smooth and pale, about 2 to 3 minutes.
Spoon the batter into the cups. Bake for 20 minutes. Remove pans from the oven and cool for 5 minutes. Then remove the cupcakes and cool on a rack.
To make the frosting, sift the confectioners' sugar in a medium bowl. Slowly add the lemon juice until the mixture becomes firm but spreadable. Spread onto the cupcakes, and sprinkle with the colored sugar.
Store unfrosted in an airtight container for up to 3 days, or freeze for up to 3 months. Makes 1 1/2 dozen.