Preheat oven to 180o C (350o F). In a large bowl, beat the egg yolks with the cream, the syrup and the scotch. Pour the mixture into a saucepan and bring to a simmer. Strain and pour into 8 large custard cups. Place the custard cups in a bain-marie and bake for 30 to 40 min, until the custard is firm. Remove the custards from the water bath and chill them.
Just before serving, sprinkle with granulated maple sugar and put under the grill until golden.