Preheat oven to 250C. Add potato to a saucepan of salted cold water, bring to the simmer over high heat, cook until tender, drain, then arrange in a 22cm x 30cm baking dish.
Meanwhile, heat oil in a saucepan over high heat, add shallot, silverbeet stalks, cavolo nero and garlic, cook until tender (4-5 minutes). Add silverbeet leaves and cook, covered, until tender (3-5 minutes), then spread over potato.
Meanwhile, for cheese sauce, melt butter in a saucepan over high heat, add flour and cook until sandy coloured (2 minutes), gradually add milk, whisking well after each addition, then add Provolone piccante and grated parmesan and stir until melted. Spoon over wilted greens, scatter over shaved parmesan and bake until golden and bubbly (10-15 minutes). Serve hot.
This recipe is from the April 2011 issue of Australian Gourmet Traveller.