• Pre-heat your oven to 180℃ Fan/370℉. Line an 8" Square Pan with greaseproof paper.
• In a small bowl, break up the chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn. Alternatively, set up a double boiler. Do this by placing a heatproof bowl over a small pot of simmering water. Add the chocolate to the heatproof bowl and stir until melted. 
• In a large mixing bowl, whisk together melted butter and both sugars - mix for at least 3 minutes. Add in the eggs, one at a time and mixing in between. 
• Add the melted chocolate slowly and combine once again. 
• Add the flour, cocoa powder. Fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Pour into the lined tin. 
• Bake 25 minutes until the top is shiny and it's still just a little wobbly in the middle. Let cool.

Make the Frosting

• Whisk the butter for about 2-3 minutes, until it's fluffy. Add the cocoa powder and half the powdered sugar. Whisk to combine, then add the remaining powdered sugar.
• Add cream (or milk) to reach your desired consistency. It should be easily spreadable!
• Spread this frosting over the brownie. Add mini M&Ms to decorate (measure with your heart).