Step 1

Preheat oven to 200C. Heat 2 tbsp oil in a frying pan over high heat, add onion, pancetta and garlic, stir occasionally until caramelised (10-15 minutes) and transfer to a casserole. Wipe out pan, add lamb and remaining oil in 2 batches and turn occasionally until lamb is browned (3-5 minutes). Transfer to casserole. Deglaze pan with wine, add to casserole with stock and rosemary, season to taste, cover and braise in oven until tender (45 minutes-1 hour).

Step 2

Transfer lamb to a bowl using a slotted spoon and keep warm. Add egg, 75gm pecorino and 75gm parmesan to casserole, whisk to combine, then return lamb to casserole with peas. Stir to combine, scatter with remaining cheeses and bake, uncovered, until custard is set and crust is golden (15-30 minutes). Serve hot.