Preheat oven (electric cooker: 200°C/ circulating air: 175°C/ gas: level 3). Rinse frozen peas with cold water and drain. Whisk eggs and milk. Season with salt and pepper. Stir in peas.
Heat the oil in a large ovenproof pan. Pour egg mixture into the pan and let it set for a short time. Crumble the feta and sprinkle over it.
Leave in a hot oven for 10-12 minutes. Pluck the ham into pieces and arrange on the finished omelette.