Place cereal in a large plastic bowl.
Melt candy melts in a double boiler or in a microwave per package instructions.
Pour melted candy over the cereal and stir to combine.
Spread coated cereal out onto wax paper and let cool almost completely.
Place cereal back into the bowl or into large baggies.
Add in the cake mix and sugar and gently shake or stir to combine.
Add in the M&Ms and gently stir.