1) Preheat oven to 210C/Gas 7.
2) Cut aubergine in half lengthwise and brush each half with 1/2 teaspoon of olive oil. Place cut side down on a nonstick baking sheet.
3) Separate garlic cloves without peeling and wrap tightly in aluminium foil. Place aubergine and garlic in oven and cook until tender, approximately 25 minutes. Allow to cool. Unwrap garlic and peel. Scrape flesh from aubergine and discard skin.
4) In a medium-sized bowl, combine garlic and aubergine. Add remaining oil, vinegar and salt and pepper, to taste, and mix until well blended.
Toast rolls and smear with aubergine spread. Layer with sliced lamb and onions. Top with buratta, mache and pesto. Garnish with mascarpone and mint.