Preheat oven to 325°F (170°C).
For cake: In a small microwave-safe bowl, warmth milk and 1¼ teaspoons (3 grams) tea leaves on excessive in 20-second intervals simply till steaming. Cowl with plastic wrap; let cool fully.
Within the bowl of a stand mixer, whisk collectively sugar, zests, and remaining 2½ teaspoons (6 grams) tea leaves by hand till sugar is aromatic. Add butter; utilizing the paddle attachment, beat at medium velocity till mild and fluffy, 2 to three minutes, stopping to scrape sides of bowl. Add eggs, separately, beating effectively after every addition and stopping to scrape sides of bowl. Beat in vanilla.
In a medium bowl, whisk collectively flour, salt, and baking powder. With mixer on low velocity, steadily add flour combination to butter combination alternately with cooled milk combination, starting and ending with flour combination, beating till mixed after every addition and stopping to scrape sides of bowl.
Spray a 10-cup Bundt pan with baking spray with flour. Spoon batter into ready pan. Firmly faucet pan on a kitchen towel-lined counter 7 to 10 occasions to degree batter and launch any air bubbles.
Bake till a wood choose inserted close to middle comes out clear and an instant- learn thermometer inserted close to middle registers no less than 205°F (96°C), 1 hour to 1 hour and 5 minutes. Let cool in pan for 10 minutes. Invert cake onto a wire rack, and let cool fully.
For topping: In a small bowl, whisk collectively sugar and tea leaves. Utilizing a pastry brush, brush melted butter onto cooled cake; sprinkle with sugar combination, gently urgent to stick. Finest served similar day as made. Retailer in an hermetic container for as much as 3 days.
