Boil some water in a sauce pan and set a mixing bowl in the pan so that the bottom doesn't touch the hot water.
Place milk chocolate in the bowl and let sit for a few minutes. Stir to melt completely. Stir until smooth.
Add cereal and mix. If desired, mix in M&M's.
Spoon into muffin cup liners or baking cups. Decorate with M&Ms.
Refrigerate until hardened. Store in an airtight container.