With the rack in the middle position, preheat the oven to 180°C (350°F). Line two baking sheets with parchment paper.
In a bowl, combine the flour, baking powder, cinnamon and salt. Set aside.
In another bowl, cream the butter with the brown sugar and vanilla using an electric mixer. Add the egg and beat until smooth. With the mixer on low speed, add the flour mixture.
Stir in the rolled oats with a wooden spoon.
With lightly floured hands, shape 75 ml (1/3 cup) of the dough into a ball. Place on a baking sheet. Repeat with the remaining dough, arranging 6 balls on each sheet. Press the balls until they are about 1 cm (1/2 in) thick. Bake 1 sheet at a time for about 13 minutes; the centre of the cookie should still be soft. Allow to cool slightly.
With a spatula, gently transfer the cookies to serving plates. Garnish each with a scoop of ice cream.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.