With the rack in the middle position, preheat the oven to 190 °C (375 °F). Butter a square 20-cm (8-inch) baking dish. Set aside.
In a bowl, combine the flour, baking powder, and salt. Set aside.
In another bowl, combine the oil and brown sugar with a whisk. Add the egg and stir to combine. Stir in the dry ingredients alternately with the milk. Spoon the batter at the bottom of the dish and place on a baking sheet. Set aside.
In a saucepan, combine the brown sugar, sugar, and cornstarch. Add the cream and bring to a boil, stirring with a whisk. Stir in the vanilla. Pour the sauce over the batter and bake for about 40 minutes or until a toothpick inserted in the centre comes out clean. Serve warm or cold.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.