With the rack in the middle position, preheat the oven to 180 °C (350 °F). Line two baking sheets with parchment paper.
In a food processor, finely grind the pecans with the flour, sugar and cornstarch. Add the butter, oil and rum and pulse a few seconds at a time until the dough begins to form.
Remove the dough from the processor. Shape into a disc with your hands and cover in plastic wrap. Refrigerate for 30 minutes.
On a floured work surface, roll out the dough into a 1-cm (1/2-inch) thick sheet. Cut cookies with a 2.5 X 3.5-cm (1 x 1 ½-inch) rectangular cookie cutter. Place a pecan half in the centre of each cookie. Place on the baking sheet and bake for about 20 minutes. Cool completely.
With a fork, drizzle the melted chocolate over cookies. Cool until the chocolate has hardened.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.