Preheat oven to 350°F.

In a medium-sized bowl, whisk together flour, sugar, 1/4 cup of the cocoa powder, baking powder and salt. Set aside.

In another bowl, using your fingers or a fork, mix together the dark brown sugar with the remaining 1/4 cup of cocoa powder. Set aside.

Heat a 12-inch cast-iron pan over medium-high heat. Once hot, add the butter to melt. Once melted, remove from the heat and add the milk. Using a rubber spatula, carefully mix in the flour, sugar and cocoa powder mixture. Once it’s combined and lump-free, spread the batter evenly across the bottom of the pan. Sprinkle the brown sugar and cocoa powder mixture evenly over the top of the batter. Pour the hot coffee over the top of the batter but do not mix it in. Place the pan into the oven and bake for 40 minutes.

After 40 minutes, remove the cake from the oven. The cake should be a little jiggly when shaken but dry and crisp on top and bubbly around the edges. Let set for a few minutes before serving over vanilla ice cream.