- With the rack in the middle position, preheat the oven to 180 °C (350 °F). Line two 20-cm (8-inch) square cake pans with parchment paper. Butter both sides of the paper.
- In a bowl, combine the flour and baking powder. In another bowl, with an electric mixer, cream the butter, sugar and vanilla until light and fluffy. Add the eggs, one at a time, beating constantly. Add the dry ingredients alternately with the milk. Combine with the electric mixer. Spread into the pans.
- Bake for about 20 minutes or until a toothpick inserted in the centre of the cake comes out clean. Unmould and let cool on wire rack.
- In a small saucepan, bring all the ingredients to a boil and simmer for 1 minute. Remove from the heat and let cool.
- Preheat the oven to 200 °C (400 °F). Soak the pecans in the egg white, then coat them generously with the brown sugar. Place on two baking sheets lined with parchment paper. Leave enough space between the pecans to keep them from touching while baking. Bake for about 10 minutes. Let cool and chop coarsely. Keep a third of the pecans to garnish the top of the cake.
- In a bowl, with an electric mixer, beat the icing sugar, butter, and maple syrup until smooth. Reserve one third of the frosting for the top of the cake. Stir in the two thirds of the pecans into the remaining frosting.
- Cut each cake in half horizontally. Remove the rounded side of one of the top slices and reserve it for the top of cake. Place a slice of cake flat on a serving plate. Drizzle with a third of the syrup, then cover with a quarter of the frosting. Repeat with two more slices of cake. Cover with the reserved frosting on the last slice of cake and sprinkle with the reserved pecans, pressing lightly with your hands.