• Preheat the oven to 350°F. Line 4 muffin pans with paper liners. (Or you can do two batches of 2 muffin pans). Set aside.
• In a large bowl, mix together the sugar, flour, cocoa powder,baking powder, baking soda and salt.
• Add in the eggs, yogurt, cold water, canola oil and vanilla. Mix until fully incorporated.
• Add in the boiling water and mix. The batter will be very thin.
• Divide the batter between the 48 muffin cavities (or 24 if you are doing two batches). Place in the preheated oven for 15-20 minutes, or until a toothpick inserted comes out clean.
• Allow to cool. Meanwhile, make the frosting.

Frosting

• Cream together the butter and cream cheese on high until light and fluffy. Reduce the speed, and add in the icing sugar and vanilla. Mix until fully incorporated. 
• Cut two long parallel lines in the centre of the cupcakes. Stick the ends of the sour rainbow strips unto the holes.
• Place the frosting in a ziplock bag or a piping bag, and pipe the frosting onto the cupcakes around the ends of the “rainbow”.