Preheat oven to 170 degrees Celsius. Wash grated potato under cold running water to remove starch and set aside to dry on some kitchen paper. Grease an ovenproof dish with half the butter.
Warm milk over gentle heat. Cut potato bread into triangles or cubes. Once the milk has warmed pour over potato bread to moisten.
Beat eggs in a large bowl, then add chopped nuts, spices, cinnamon, liqueur and cherries, caster sugar and potato bread. Combine gently and pour into an ovenproof dish. Sprinkle pine nuts, grated potato, and raw sugar. Dot the topping with remaining butter.
Bake for 20-25 minutes or until golden and bubbling. Serve with fresh cream or custard