In a large bowl, whisk together flour, cocoa powder, baking powder, baking soda, salt.
In another bowl, whisk together the oil, sugar, vanilla extract and milk.
Add vinegar. Combine well.
Add the dry ingredients little by little.
Gently combine together to make a smooth and lump free batter.
Heat your paniyaram (appe) pan on low flame and grease each cavity with a few drops of oil or butter.
Once the pan is slightly hot, reduce the flame to low-medium. Pour a spoonful of batter into each cavity, filling about half of it.
Place a small piece of chocolate in the center of each.
Cover the chocolate with a little more batter so it’s sealed inside completely.
Cover the pan with a lid and cook for 2 minutes on low heat.
Once you see the edges firming up, gently flip each appe using a skewer or spoon. Cook the other side for another minute until both sides are evenly browned.
Take the paniyarams out carefully and let them cool for 2 minutes.
When you cut them open, you’ll see melted chocolate in the center.
You can add chopped nuts, powdered sugar on top or drizzle caramel sauce or melted chocolate once they’re done.