Mix all ingredients A together.
Mix all ingredients B in a bowl and pour ingredients A into ingredients B.
Keep mixing and kneading until it forms into a dough.
Let it rest for 45 minutes.
Divide dough into 4 portions. Roll out dough into a square, place some caramelized onions then put lots of shredded mozzarella cheese.
Fold the dough to secure the cheese and seal the sides.
Roll it out again to thin it evenly and then place it on a cooking pan.
Cook on every side until it is golden brown.
For the cheese sauce, cook butter and flour onto a cooking pan until it thickens.
Add in milk and keep stirring until it has slightly reduced.
Add in cheddar cheese until they are melted.
Pour onto cheese naan bread and serve.