Whisk the oats, salt, baking powder and cacao powder in a bowl. Pour in the milk, whisk, then add the peanut butter and maple syrup and keep whisking until well combined.
Transfer to a mini cake pan and dip the chocolate squares in the batter.
Drizzle a little peanut butter on top and bake for 10-12 minutes. Remove from the oven and let it rest for 5 minutes.