1 1/2 cups (3 sticks) unsalted butter, cut into pieces
1 cup freshly brewed coffee
1/2 cup water or milk
3/4 cup unsweetened Dutch-process cocoa
3 cups all-purpose flour
3 1/4 cups granulated sugar
3/4 teaspoon baking powder
3/4 teaspoon fine salt
1/2 teaspoon baking soda
3/4 cup sour cream
3 large eggs, room temperature
1 1/2 teaspoons pure vanilla extract
Confectioners' sugar, for dusting
6 ounces semisweet chocolate, finely chopped
1/2 cup canned unsweetened coconut milk
1 to 2 tablespoons corn syrup
1 1/2 cups unsweetened coconut chips or shredded coconut, lightly toasted
We prefer Dutch-process cocoa here over natural cocoa for its fuller, deeper flavor.