Combine flour, onion, powder, nigella seeds and salt in a bowl. Add yoghurt. Using your hands, mix and knead until a rough balls forms. Cover and set aside for 15 minutes for the dough to relax.
Gently knead the dough again to achieve a smooth ball then divide into 4 equal portion. Shape each portion into a small ball by rolling on it quickly on a dry bench top under the cupped palm of your hand. Set aside and repeat.
On a lightly floured surface, roll out each portion of dough until 3-4mm in thickness, in an oval shape, similar to a store bought naan bread.
Heat a frying pan over medium high heat. Working with one naan at a time, cook for 1 ½ - 2 minutes until the underside is lightly golden and top of the naan bread had large random bubbles over it. Turn over, then cook the other side for about 1 minute until those bubbles have browned. Transfer naan to a clean towel and wrap to keep warm. Repeat with remaining naan breads. Serve warm as they are or brush with the Garlic Butter below.