- Preheat the oven to 325 °F (160 °C).
- Steep the tea bags in the boing water until the water cools to room temperature. Without squeezing out excess liquid, remove the bags, then top up with water to its original ¾ cup (185 mL) measure.
- Whip the egg whites with the cream of tartar until foam, then add ¼ cup (50 g) of the sugar and continue whipping until the whites hold a medium peak. Set aside.
- Sift the flour, the remaining 1 ¼ cups (250 g) of the sugar, the baking powder, and the salt into a large bowl or into the bowl of a stand mixer fitted with the whip attachment. Add the cooled tea, oil, egg yolks, vanilla, and the melted milk chocolate and whip it on low speed until blended. Fold in half of the whipped egg whites by hand until they are incorporated, then fold in the remaining whites (the batter will be quite fluid). Pour this into the 10-inch (25 cm), ungreased tube pan.
- Bake the cake for 50 to 55 minutes, until the top of the cake springs back when gently pressed. Invert eh cake pan onto a cooling rack and cool the cake upside down in its pan. To extract the cake, run a spatula or knife around the outside edge of the cake, then tap the cake out onto a plate.
- Use a spatula to spread the maple meringue over the entire surface of the cake (use a small spatula or butter knife to frost the cake inside the centre hold). Store the cake at room temperature until ready to serve and cover the interior cake with plastic wrap only one cut. The cake will keep for up to 3 days.