In a microwave-safe bowl, microwave 1 ¼ cups chocolate chips and ½ cup peanut butter on high in 30 second bursts - stirring in between - until completely melted.
Add a pinch of salt and stir until incorporated and smooth.
Add 2 cups of cornflakes and stir until cornflakes are covered in chocolate (see notes).
Scoop the mixture into your cupcake cups then top with M&Ms (see notes). Chill in the fridge overnight or until set.
Video
Notes
It's OK to crush some, most or all of the cornflakes!
If you don't have a cupcake pan or candy liners, you can also scoop the mixture onto a baking sheet lined with parchment paper. Try to form them into tight balls.