Ingredients

1 stick unsalted butter, room temperature, plus more for pan

1 1/2 cups all-purpose flour, plus more for pan

1/2 teaspoon baking powder

1/4 teaspoon baking soda

3/4 teaspoon coarse salt

1 (5.4 ounce) can cream of coconut

1 teaspoon pure vanilla extract

1/4 cup coconut oil

1 cup sugar

3 large eggs

2 large egg whites

1/8 teaspoon coarse salt

1 can (14 ounces) sweetened condensed milk

2 teaspoons pure vanilla extract

3 cups sweetened shredded coconut (8 ounces)

1/3 cup heavy cream

1/4 cup sugar

4 ounces bittersweet chocolate, chopped

2 tablespoons unsalted butter

2 teaspoons pure vanilla extract

Preparation

Cake: Preheat oven to 350 degrees. Butter and flour a 10-inch springform pan. Whisk together flour, baking powder, baking soda, and salt. In another bowl, stir together cream of coconut and vanilla.

Beat butter and coconut oil on medium-high until smooth. Slowly add sugar; beat until pale and fluffy, 3 to 5 minutes. Reduce speed to medium; add eggs, one at a time, beating well after each and scraping down sides of bowl as needed. With mixer on low, add flour mixture in 3 batches, alternating with 2 batches of cream-of-coconut mixture. Beat until just combined.

Topping: In a large bowl, whisk together egg whites and salt until thick and frothy, about 1 minute. Stir in milk and vanilla. Fold in coconut.

Spread cake batter in pan. Pour topping over batter; carefully spread in an even layer. Bake on a rimmed baking sheet until a toothpick comes out with just a few moist crumbs, about 1 hour (tent with foil if browning too quickly).

Chocolate Sauce: In a small saucepan, bring heavy cream and sugar almost to a boil, stirring, until sugar is dissolved. Pour over chocolate and butter in a heatproof bowl. Stir until smooth, then stir in vanilla.

Let cake cool completely; remove from pan. Cut into wedges, drizzle with chocolate sauce, and serve with extra sauce on the side.