Heat the oil in a medium frying pan and add the onion. Cook for 2-3 minutes until starting to soften. Add the garlic, ginger, chopped chillies, garam masala, ground coriander, cumin, turmeric, chilli powder, salt and pepper. Fry, stirring regularly for 2 minutes until the fragrance is released.
Add the lamb, and mixt together. Cook, stirring regularly, until the lamb is browned (about 5 minutes). Add in the peas and stir. Turn off the heat.
Whilst the lamb is cooking, lay the filo sheets out and brush melted butter on top of each sheet. Layer up the sheets, so you have 2 piles of 3 sheets. Use a 98mm (3+7/8") cookie cutter* to cut out circles. You should get at least 12 rounds (you may get a few more depending on your filo pastry sheet size).
Take a 12-hole shallow bun tin, and brush with melted butter. Fill each hole with a pile of the filo sheets. Squash them in, all the way to the edges.
Spoon in the lamb mixture and brush any pastry on show with melted butter.
Place in the oven for 12-15 mins until the filo pastry is crisp and browned.
Remove from the oven and serve hot, topped with a sprinkling of fresh coriander and chilli flakes.
*If you haven't got a cookie cutter, you can cut each pile into 6 squares, so you have 12 little piles altogether. You'll need to trim them with scissors once you have pushed them into the muffin tin.If making ahead, cook for 5 minutes less than stated, then cool, cover and refrigerate for up to one day. Reheat for 7-8 minutes at 175C/350F until piping hot..Nutritional Information is per serving.