Greek lamb and feta layer

Name: Greek lamb and feta layer
Ingredients: 5 tbsp. olive oil; 1 lg onion, finely chopped; 900 g (2lb) lamb mince; 2 clv garlic, crushed; 2 tbsp. tomato puree; 2 x 400g cans cans plum tomatoes in tomato juice; 3 tbsp. worcestershire sauce; 2 tbsp. chopped fresh oregano; 3 lg potatoes – about 1kg (21⁄4lb); 2 lg aubergines, trimmed and cut into 5mm (1⁄4in) slices; 2 x 500g tubs Greek yoghurt; 4 lg egg; 50 g (2oz) freshly grated Parmesan cheese; 1 pinches grated nutmeg; 200 g (7oz) feta cheese, crumbled