- With the rack in the middle position, preheat the oven to 180°C (350°F). Using a brush, generously butter the inside of a castle-shaped novelty cake pan (see note) or a 23-cm (9-inch) tube cake pan.
- In a bowl, combine the flour, cornstarch and baking powder. Set aside.
- In another bowl, cream the butter and sugar with an electric mixer. Add the eggs one at a time and continue beating until the mixture is smooth and light. Add the vanilla.
- With the mixer on low speed, add the dry ingredients, alternating with the milk. Pour the batter into the pan and bang it sharply on the counter to eliminate any air bubbles. Bake until a toothpick inserted in the centre comes out clean, 40 to 45 minutes. If you used a novelty cake pan, let the cake cool for about 30 minutes. Unmould and let cool completely.
- Place the cake on a platter. Surround with brown sugar “sand.”