Preheat the oven to 180?
Chop the courgettes and red peppers into pieces about the same size as the baby potatoes. Half any potatoes that are much bigger than the others.
Arrange the courgettes, red peppers and potatoes in the base of a large roasting pan. Add the tomatoes, olives and diced chorizo.
Place the chicken on top and drizzle with the olive oil, season with salt and pepper.
Put in the oven on the middle shelf and cook for one hour – check that the juices run clear when you stab the chicken with a skewer
While the chicken is cooking, make the yoghurt. Peel and grate the garlic cloves, then stir into the yoghurt along with a pinch of salt and pepper.
After an hour, remove the chicken from the oven and let it rest for 10 minutes. You can cover in foil to keep everything warm.
To serve, give everyone a big spoonful of the roasted vegetables and pieces of chicken. Drizzle with the yoghurt and a little olive oil.