Firstly,cut the bread pieces in circle shape with the help of cookie cutter,or a glass.

Mix onion,potato, coriander leaves,salt,black pepper,in a bowl and make a dough or bharta of it.

Than apply some sauce on one layer of bread.

Above the sauce put some potato dough like tikki.

In 2nd layer again put some sauce and cover the potato with it.

Than make a thick paste of dahi in a bowl removing it's excess water,add some salt and black pepper for flavour.

Than on top layer of sandwich apply this paste of dahi with the help of a spoon.

Make a smiley using sauce,or decorate it with whatever you wants.

And serve it

Your children can also make this oneself.