Preheat the oven to 200degrees fan-bake. In a large mixing bowl, cream the butter and sugar until just combined. Add in condensed milk and fold together.
Sift in flour and baking powder and mix with a wooden spoon.
Sprinkle in the vegan chocolate M&Ms (or sub for vegan choc chips) and roll the dough into small balls. Flatten cookies and place them on a baking paper lined tray in the fridge for at least 10 minutes.
Remove from the fridge and bake for 15 minutes. Leave to cool for 30 minutes before enjoying.