Sprinkle the yeast on surface of the water in a small bowl and add 1 teaspoon of golden caster sugar. Leave to bubble up and become frothy. This takes about 10-15 minutes
In a large bowl put the strong bread flour, baking powder, the other teaspoon of golden caster sugar and the salt and give it a good old mix
Make a well in the centre if the flour mix and sprinkle in the nigella seeds, pour in 25g of the melted butter, the yoghurt and the yeast mixture. Mix together until you have a sticky dough, not too wet it should just hold in a ball
Turn the ball of dough out onto a well floured surface and knead for about 10 minutes. You'll know when it's ready because it will be smooth and elastic.
Place the kneaded dough into a fresh large bowl that has been greased with some of the remaining melted butter and cover with a damp tea towel. Leave to rise for 2 hours. The original recipe said 1 hour but we find 2 hours gives a much better end result!
Stick the oven on a very low setting about 10 minutes before you're going to start cooking to keep the cooked naan breads warm
Once the dough is well risen turn it out onto a well floured surface and divide the mixture into 6 roughly even balls (this dough freezes perfectly at this stage!)
Put a dry frying pan (or chapati pan if you have one) onto a high heat and get it as hot as you can. Whilst the pan is heating up, roll out the first dough ball into a tear shape that is about 2-3mm thick
Put the rolled out dough carefully onto the very hot pan and cook for about 3 minutes until it bubbles up. Whilst this is cooking roll out the next dough ball ready to be cooked.
Turn the bubbled dough over and cook until it chars. Once nicely charred transfer it to a roasting tin, brush liberally with more of that melted butter (which you will have re-melted by now) and cover with tin foil. Repeat with next dough ball until you have cooked all of the naans you want. Freeze any dough balls you don't want to use right now. Enjoy! We do!