Add sugar and yeast to the lukewarm water and let it sit for 10 minutes to activate. Once the yeast is activated you can proceed with making the dough.
In a bowl, take the refined flour, salt, yogurt and egg. Give it a mix.
Add the yeast water and mix again.
Finally add the lukewarm milk as necessary and knead to make a sticky dough.
Apply the oil and cover the dough with a damp muslin cloth. Set this aside for 2 - 3 hours till the dough rises to be double in size.
When the dough has risen, remove the muslin cloth and knead to make a smooth dough.
Take a ball and roll out a thick disc like chapati. You can make it into any shape that you like.
Prick the rolled out naan with a fork.
Heat a tawa and cook till the bottom part is golden brown in color.
Transfer to a baking pan and cook the top part under a grill. (Alternatively, cook the top on gas flame)
When the naan turns golden brown in color, remove and apply butter on top.
Serve naan hot with any curry that you love.