Preheat oven to 180 degrees celsius (160 fan-forced).
Grease and line an 18X28cm rectangular slice tin with baking paper.
Place butter and dark chocolate melts into a microwavable-safe bowl.
Melt on 50% power for 3-4 minutes, stirring every 30 seconds with a dry metal spoon.
Set aside.
Sift plain flour, salt, baking powder and cocoa into a large bowl.
Add the brown sugar, white sugar and milk chocolate chips and mix together with a wooden spoon.
Whisk the eggs lightly and add to the bowl.
Pour in the melted chocolate/butter mixture.
Mix with a wooden spoon until just combined.
Pour into the prepared tin and bake for 25-30 minutes or until a skewer inserted into the middle comes out clean.
Recipe Notes
TIPS FOR FREEZING SLICES
you can freeze the slices as a whole or cut into individual pieces;
wrap the slice in plastic wrap then wrap in a layer of foil and place into an airtight container in the freezer (these 3 steps will keep your slices tasting great!);
slices with a soft filling (or cheesecakes) don’t tend to freeze well;
slices kept in the freezer will taste best within the first month, but can last longer.