1. To make the cake, preheat the oven to 325F. Spray a PADERNO Non-Stick Fine Edge Arched Cake Pan with baking spray (or grease with butter and sprinkle with flour).
2. Whisk the flour with the sugar, cocoa powder, baking soda, baking powder and salt in a large bowl. In a small bowl, whisk the eggs, then whisk in the milk, canola oil and vanilla. Pour the egg mixture into the flour mixture and stir to combine. Add the water and stir until well-combined.
3. Scrape the batter into the prepared pan. Firmly tap the pan on the counter once to release any large air bubbles. Bake for 45 - 50 minutes or until a cake tester inserted into the centre comes out clean. Let cool for 5 minutes, then flip out onto a rack to cool completely.
4. To make the ganache, heat the cream in a very small pot until just simmering. Tear open the tea bags and add the tea leaves to the cream. Remove from the heat, cover and let stand for 10 minutes. Strain through a fine-mesh strainer. Add vanilla and a pinch of salt to the cream mixture.
5. Clean out the pot and return the cream mixture into the pot. Heat to just simmering, then add the chopped white chocolate and cook very gently, stirring constantly, until chocolate is almost melted. Remove from heat and let stand, stirring constantly, until chocolate is completely melted. Let cool completely, then pour over the cooled cake.
