Preheat the grill [broiler] to high.
Lightly grease a medium sized flameproof baking dish with the teaspoon of butter.
In a medium sized saucepan, melt half of the remaining butter over moderate heat.
Remove the pan from the heat and, with a wooden spoon, stir in the flour to make a smooth paste.
Gradually add the milk, stirring constantly.
Return the pan to the heat and cook, stirring constantly, for 2 to 3 minutes, or until the mixture is thick and smooth.
Add the nutmeg and 2 tablespoons of the sugar.
Reduce the heat to low and simmer for 3 minutes.
Remove the pan from the heat.
Pour the mixture into the baking dish and dot the surface with the remaining butter, cut into small pieces.
Sprinkle the remaining sugar and the cinnamon thickly on top of the butter.
Place the dish under the grill [broiler] and cook for 3 to 5 minutes or until the top is golden brown.