Mix the baking powder, cinnamon and sugar in a bowl.
Add the eggs, rum and melted butter and beat well.
Gradually, while stirring continuously, add the flour.
Let the resulting batter sit for about 2 hours at room temperature without covering the dish.
Preheat the waffle iron. Smear it with butter before you place each subsequent waffle in it.
Bake the waffles and serve them with a sweet filling.