Preheat the oven to 180°C (350°F) and line a 9'x9' baking tin with baking paper.
Caramilk Brownie Layer;
Melt the butter and Caramilk chocolate together.
Beat the egg, brown sugar, sugar and vanilla extract together until light.
Mix in the chocolate mixture.
Mix in the flour and baking soda and add the chocolate chips.
Pour into the base of the of the baking pan and set aside while you make the chocolate brownie layer.
Chocolate Brownie Layer;
Melt the butter and dark chocolate together.
Mix the eggs, sugar, brown sugar and vanilla extract together until the mixture becomes a light golden colour.
Mix in the chocolate mixture.
Stir in the flour and cocoa until just combined.
Add in the caramilk chocolate chips and mix through
Spread the mixture overtop of the caramilk brownies and place in the oven for 30-35 minutes. The top and sides will be set and the middle will have crumbs attached to a skewer inserted but should not be wet.
Allow to cool for 10 minutes in the pan and then remove to cool on a rack until room temperature before slicing and serving
Notes
If you can't get your hands on Cadbury Caramilk, you can use any other caramelised white chocolate.
If you don't have caramilk chocolate chips, you can chop up caramilk into small peices and mix those through.