Preheat the oven to 150°CC/300°CF/Gas 2.
Parboil the potatoes in boiling salted water for 4-5 minutes until just tender. Drain thoroughly.
Heat the oil in a heavy-based frying pan and sauté the potatoes until crisp and golden on all sides for 15-20 minutes, sprinkling with rosemary halfway through cooking. Season, put into an oven-proof dish and keep warm in the oven.
For the courgettes, heat the olive oil in a pan and gently fry until tender and lightly gold. Season and squeeze over the lemon. Keep warm and set aside.
Put each turkey steak between two pieces of clingfilm and bash out with a rolling pin until 1cm thick. Lay out the prosciutto slices and lay an escalope on top of each one.
Sprinkle each escalope with Parmesan and a little salt and pepper. Roll the escalopes in the prosciutto to make a Swiss roll.
Heat the oil in a frying pan and cook the turkey rolls for six to eight minutes, turning frequently, until cooked through with no pink showing. Set aside to rest.
Sprinkle the torn basil leaves over the courgettes.
Serve each turkey roll sliced in half to allow the cheese to ooze out alongside the potatoes and courgettes.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.