Preheat the oven to 350°F (175°C) and prepare a 9x13 inch baking pan by greasing it.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.

In a separate bowl, combine the hot coffee, milk, vegetable oil, and eggs, whisking until smooth.

Gradually pour the wet mixture into the dry ingredients, mixing gently until just combined.

Pour the batter into the prepared pan and bake for about 30 minutes, checking for doneness with a toothpick.

Let the cake cool in the pan for about 10 minutes, then poke holes across the surface.

In a microwave-safe bowl, combine chocolate chips and sweetened condensed milk, heating until melted and smooth.

Pour the filling evenly over the poked holes of the cake and let it soak as the cake cools completely.

Whip the heavy cream with powdered sugar and cocoa powder until soft peaks form.

Spread the whipped cream over the cooled cake and refrigerate for at least 1 hour before serving.