Throwdown's Toasted Coconut Cake with Coconut Filling and Coconut Buttercream

INGREDIENTS

• 1 tablespoon granulated sugar
• 12 tablespoons unsalted butter, cut into 12 pieces, slightly cold
• 4 large egg yolks
• 3/4 cup unsweetened coconut milk
• 3/4 cup very cold heavy cream
• 3 tablespoons cornstarch
• 2 teaspoons coconut rum (recommended: Malibu)
• 1/2 vanilla bean, seeds scraped
• 3/4 cup coconut custard (recipe above) (cold)
• 3/4 cup whole milk
• 1 vanilla bean, split and seeds scraped
• 1 3/4 cups granulated sugar
• 1 cup whole milk, at room temperature
• 1/3 cup confectioners' sugar
• 2 cups sweetened flaked coconut
• 3/4 cup coconut custard (recipe above), cold
• Pinch fine sea salt
• 1 tablespoon plus 1 teaspoon baking powder
• 1/2 teaspoon pure vanilla extract
• 2 tablespoons softened butter, for pans
• 2 1/4 cups cake flour, plus more for pans
• 1 teaspoon fine sea salt
• 1 1/2 cups water
• 6 large egg whites, at room temperature
• 3/4 cup sweetened flaked coconut
• 1/3 cup granulated sugar
• 3 stick unsalted butter, softened