- With the rack in middle position, preheat oven to 180 °C (350 °F). Line a 43 cm x 30-cm (17 x 12-inch) baking sheet with parchment paper, letting the paper hang over 2 opposites sides. Butter the other sides.
- In a bowl, combine the flour, cocoa, baking powder and salt. Set aside.
- In another bowl, cream the butter with the sugar, vanilla and food coloring using an electric mixer. Add the eggs, one at a time, beating constantly until the mixture is smooth. With the mixer at low speed, add the dry ingredients alternating with the milk. Spread the batter on the baking sheet. Bake approximately 15 minutes or until a toothpick inserted in the centre of the cake comes out clean. Cool completely. Unmold and put the parchment paper back on the baking sheet. Set aside.
- In a small saucepan, combine the sugar, water and corn syrup. Bring to a boil and cook until the candy thermometer reads 116 °C (240 °F). Remove from the heat while whipping the egg whites.
- In a bowl, beat the egg whites and cream of tartar with an electric mixer until soft peaks form. Pour the syrup over the egg whites, beating continuously until the meringue is barely warm and form stiff peaks. Stir in vanilla.
- In the top part of a double boiler, melt the chocolate with the oil. Remove the top part of double boiler. Let it cool.
- Using a cookie cutter of about 9-cm (3 ½-inch) in diameter, cut out twelve circles in the cake. Using a pastry bag fitted with a plain tip, spread the desired amount of meringue on six circles. Cover with a circle of cake. Place on baking sheet. Freeze 15 minutes.
- Using your hands, dip the edge of each cake into the chocolate. Using a spoon, cover top of cake to coat well. Set aside on a rack and let the chocolate set in a cool place at least 1 hour.