Scrub the potatoes and cut lengthwise into wedges. Melt the butter in a large saucepan then remove the pan from the heat and stir in the ground cinnamon. Toss the potato wedges in the butter to coat them completely then season with 2 teaspoons of salt and 1 teaspoon of freshly-ground black pepper.
Spread the potatoes in an even layer on a baking sheet and roast in a preheated moderately hot oven (Mk 6 - 400ºF - 200ºC) for 25-30 minutes until golden and tender, turning wedges after the first 15 minutes. Serve hot.