Recipe from “Back to Baking”, Whitecap Books 2011.
Makes one 10-inch tube cake
Preheat the oven to 325 F. Keep a 10-inch tube pan ungreased.
Steep the tea bags in the boiling water, until the water cools to room temperature. Remove the bags, without squeezing out excess liquid, then top up the water to its original ¾ cup measure.
Whip the whites with the cream of tar until foamy, then add ¼ cup of the sugar and continue whipping until the whites hold a medium peak. Set aside.
Sift the flour, the remaining 1 ¼ cups of the sugar, the baking powder, and salt into a large bowl or into the bowl of a stand mixer fitted with the whip attachment. Add the cooled tea, the vegetable oil, egg yolks, vanilla and lemon zest. Whip this mixture on high until it is thick, about 4 minutes. Add the melted milk chocolate and whip in on low speed. 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).
Bake the cake for 50 to 55 minutes, until the top of the cake springs back when gently pressed. Invert the 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.
To prepare the maple meringue, whip the egg whites with the cream of tartar until foamy, then add the sugar and whip the whites just to a soft peak. Bring the maple syrup to a boil and cook uncovered and without stirring until it reaches a temperature of 242 F (softball stage) on a candy thermometer. While beating on medium speed, carefully pour the maple syrup into the meringue by pouring it down the side of the bowl (this will help prevent splashing of hot syrup) and continue whipping until the mixture has cooled but is not quite room temperature, about 3 minutes. Stir in vanilla.
Use a spatula to spread the meringue over the entire surface of the cake (use a small spatula or butter knife to frost the cake inside the center hole. Store the cake at room temperature until ready to serve and only cover with plastic wrap the interior cake once cut.