Triple Layer Chocolate Matcha Cake

Name: Triple Layer Chocolate Matcha Cake
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: Asian
Ingredients: 2 2/3 cups sparkling water; 1 1/3 cups dark unsweetened cocoa powder; 1/2 cup (plus 3 tablespoons (155g), unsalted butter, cubed (plus more for cake pans)); 2 cups granulated sugar; 3/4 cup brown sugar; 2 2/3 cups all-purpose flour; 2 teaspoons baking soda; 2 teaspoons salt; 3 large eggs; 3 sticks unsalted butter (room temperature); 4 cups powdered sugar; 2 tablespoons matcha powder; 2 teaspoons whole milk