1. For the Lamb, lightly score the skin and place it fat side down on a board.
2. Combine all the ingredients for the filling and place into the lamb. Roll and truss. 
3. Pour boiling water over skin then completely dry.
4. Season generously with sea salt and refrigerate uncovered overnight. 
5. Remove from the refrigerator 1 hour before cooking. 
6. Remove excess salt, rub with olive oil and re-season with fresh sea salt.
7. Roast at 220°C fan for 15 minutes to develop the crust.
8. Reduce the oven to 160°C for approximately 50 minutes, or until internal temperature reaches 53°C.
9. Rest 30 minutes before removing string and slicing. 
10. For the Potato Cream, toss potatoes with half the olive oil, salt and pepper.
11. Roast for 30–35 minutes at 200°C until golden. Cool slightly.  
12. Blend potatoes with Parmigiano, garlic, remaining olive oil and water to a puree.
13. Adjust with additional water if required. Season.
14. For the Parmesan Cream, warm the milk. 
15. Melt butter over medium heat, whisk in flour to form a roux. Slowly add warm milk while whisking continuously. Cook until smooth and thickened. Add parmigiano. 
16. For the Salsa Verde, Combine all ingredients in a food processor.
17. Pulse until finely chopped but not completely smooth. Season. 
18. For the Broccoli and Fennel, combine all ingredients. Roast at 220°C for 10 mins, until well caramelized. Cool
19. For the Grapes, combine all ingredients. Chill. 

Sandwich assembly

1. Butterfly and lightly toast bread
2. Spread potato cream on the base
3. Place 150g of lambchetta on top, drizzle with salsa verde
4. Top with grapes, roasted fennel and broccoli 
5. Spread the top with parmesan cream 
6. Serve immediately.