Fudgy Coconut Cream Cake

Name: Fudgy Coconut Cream Cake
Ingredients: 8 tablespoons (113g) unsalted butter at room temperature at least 65°F; 2 cups (397g) granulated sugar; 4 ounces unsweetened baking chocolate melted and cooled; 4 large eggs at room temperature; 1 3/4 cups (206g) King Arthur Unbleached All-P; 1 teaspoon baking soda; 1/2 teaspoon baking powder; 1/2 teaspoon salt; 1 cup (241g) canned unsweetened coconut milk well shaken; 1/2 cup (113g) buttermilk at room temperature; 1 teaspoon strong coconut flavor optional; 1 teaspoon vanilla extract; 2/3 cup (120g) butter-flavored shortening or 5 1/3 tablespoons (71g) butter + 1/3 cup (60g) vegetable shortening at room temperature at least 65°F; 2 tablespoons (14g) coconut milk powder optional; 1 teaspoon strong coconut flavor optional; 1 teaspoon vanilla extract; 1 tablespoon canned unsweetened coconut milk; 1/8 teaspoon salt; 2 cups (227g) confectioners' sugar sifted; 1 1/2 cups (198g) marshmallow creme; 6 tablespoons (85g) butter softened; 3 ounces unsweetened baking chocolate melted and cooled; 5 to 6 cups (567g to 680g) confectioners' sugar sifted; 1 teaspoon vanilla extract; 1/2 teaspoon strong coconut flavoring optional; pinch of salt; canned unsweetened coconut milk as needed to adjust consistency