Mexican Hot Chocolate Cake With Ganache Frosting

Ingredients

• 9 tablespoons unsweetened cocoa powder
• 1½ cups minus 2 tablespoons unbleached pastry flour
• 2 tablespoons cornstarch
• 2 tablespoons cinnamon
• 1 tablespoon cayenne pepper (or 1 teaspoon habenero powder + ½ tablespoon ancho chili powder which is what i used)
• ½ teaspoon salt
• 1 teaspoon baking soda
• ¼ teaspoon baking powder
• 4 ounces (1 stick) unsalted butter, at room temperature
• 1½ cups granulated sugar
• 2 large eggs, at room temperature
• ½ cup water
• ¾ cup whole milk
• 10 ounces bittersweet or semisweet chocolate, coarsely chopped
• ½ cup water
• ¾ cup (1½ sticks) unsalted butter