Preheat oven to 425°F. Line a 12 cup muffin/cupcake tray with paper liners or spray well with non-stick cooking spray, making sure to spray the sides as well.
In a large bowl, combine your flour, baking powder, baking soda, salt and chocolate chunks.
In a separate medium bowl, whisk together your melted and cooled butter, sugar, egg replacer, milk and vanilla extract.
In the bowl with your dry ingredients, create a crater in the center and slowly add your wet ingredients to your dry ingredients. Fold together until just combined. Be careful not to overdo it.
Divide the batter into the 12 muffin cups and bake at 425°F for 5 minutes. Then reduce the oven temperature to 375°F and continue to bake for approximately 15 minutes or until a toothpick inserted into the center comes out clean. Ovens vary greatly, so make sure you are monitoring in the last few minutes to avoid dry muffins.