1. Add the tinned tomatoes to an ovenproof tray (use one which has some depth to it).
2. Add dried oregano, salt, pepper, and oil.
3. Slice the onion and add this to the tray.
4. Using a spoon, mix the onions into the tomatoes.
5. Then add the chicken (whole or halve the thighs) into the tomato and make sure they are sat into the sauce.
6. Cook this into a preheated oven at 200 degrees for about 20 minutes.
7. After 20 minutes, add the grated cheese on top and place it back into the oven for another 10 minutes or until the cheese has melted and the chicken is cooked.
8. Serve with some steamed or roast potatoes.
9. Enjoy!