Dan Doherty's Jerusalem artichoke gratin with sweet onion and hazelnut crumble

Dan Doherty's Jerusalem artichoke gratin with sweet onion and hazelnut crumble

    • Serves8
    • CourseMain meal
    • Prepare40 mins
    • Cook1 hr 25 mins
    • Total time2 hrs 5 mins
    • Plusinfusing
    • 600ml double cream
    • 1 sprig rosemary
    • 3 garlic cloves
    • 400g maris piper potatoes, peeled and sliced 0.25cm thick (using a mandoline)
    • 800g Jerusalem artichokes (or celeriac), peeled and sliced 0.25cm thick (using a mandoline)
    • 80g parmigiano reggiano, finely grated

    CRUMBLE

    • 40g hazelnuts
    • 50g oats
    • 30g salted butter
    • 2 medium onions, diced
    • 2 garlic cloves, finely chopped
    • 1 sprig thyme
    • 25g flat leaf parsley, finely chopped