Preheat the oven to 180˚C/160˚C fan/gas mark 4. Line a 12-hole muffin tin with six green and six orange Dr. Oetker Rainbow Cupcake Cases.
In a large bowl, beat together the butter and sugar until light and fluffy. Add the eggs one at a time, beating between each addition.
Stir in the flour, Dr. Oetker Fine Dark Cocoa Powder, Dr. Oetker Baking Powder and Dr. Oetker Madagascan Vanilla Extract. Mix until just combined, then stir in the milk. Fold through the Dr. Oetker Milk Chocolate Chips. Spoon the mix into the prepared cases.
Bake for 15-20 minutes or until a skewer inserted into the centre of a cupcake comes out clean. Allow to cool completely.
In a large bowl, add the two tubs of Dr. Oetker Vanilla Buttercream, reserve 2 tbsp for later. Add a few drops of Dr Oetker Extra Strong Green Food Colour Gel or until you get your desired colour. Mix until the colour is combined.
Spoon the buttercream into a piping bag with a star nozzle. Pipe a swirl of buttercream on top of each cupcake.
To make the pot of gold, take a small piece of Dr. Oetker Black Coloured Fondant Icing and roll into a ball. Use your thumb to hollow out the centre. Use your hands to shape the ball into a cup shape.
Roll a skinny log of fondant for the rim of the pot. Brush a little water/buttercream around the edge of the pot to act as glue, then stick the fondant rim to the pot.
Brush the inside of the pot with some water/buttercream. Pour in some Dr. Oetker Glamour and Sparkle Sprinkles (the water/buttercream will help it stick to the pot). Repeat these steps to make 12 pots of gold.
Stick the pots of gold on top of each cupcake. Cut the fizzy rainbow belts into smaller strips. Stick the fizzy belt inside the pot of gold and arch over the side. Use the remaining 2 tbsp of buttercream to pipe a small line at the base of the fizzy belt to make it look like a cloud. Repeat for all 12 cupcakes.