Preheat your oven to 350°F (175°C). Grease a 9-inch round or square baking pan with butter or cooking spray.

In a large mixing bowl, whisk together all-purpose flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt. Add egg, vanilla extract, milk, and vegetable oil, whisking until smooth. Gradually stir in hot coffee.

Pour the batter into your prepared pan. Bake for 25 minutes or until a toothpick inserted into the center comes out clean.

While the cake is baking, melt unsalted butter in a skillet over medium heat. Add kataifi and cook until golden, about 5-7 minutes. Mix crispy kataifi with pistachio cream in a bowl.

In a microwave-safe bowl, combine chocolate bar and heavy cream. Heat in the microwave in 20-second intervals until melted and smooth.

Once the cake has cooled, remove it from the pan and place it on a serving plate. Spread the pistachio filling over the top of the cake, then pour the chocolate mixture over the filling.

Garnish with additional pistachio sauce, toasted kadaifi, or crushed pistachios. Allow to set before slicing.