Preheat the oven to 175 degrees Celsius.
Melt the coconut oil and let it cool while preparing the rest of the ingredients.
Combine milk and apple cider vinegar in a bowl and let it sit for a few minutes while you prepare the rest of the ingredients.
Grease four muffin tins.
Add the milk mixture, stevia drops, coconut oil and apple sauce to a blender and blend until smooth.
Combine flour, cacao powder, stevia sugar and baking powder in a bowl.
Add the dry ingredients to the blender and mix until smooth.
Fill the muffin tins halfways, put 1-2 squares of chocolate in the middle of the tins and then fill up the rest of the muffin tins.
Repeat with remaining batter.
Bake in the middle of the oven for 10-15 minutes, until a toothpick comes out clean after inserting it on the side of the muffin. Don't insert it in the middle since it will come out wet from the melted chocolate.
Serve while warm.