In a medium bowl whisk together the flour, sugar, cocoa, baking powder, and salt.
Stir in the milk, butter and vanilla until just combined to create a batter. It may be slightly lumpy but that is okay.
Gently fold in 1 cup of fresh raspberries. Set aside the remaining for garnish before serving.
Pour the cake batter into an un-greased 9×13 baking dish and spread evenly through the dish.
Next, add the brown sugar and espresso powder into a bowl and pour in 1 cup boiling water.
Stir until the sugar has dissolved and pour directly over the cake batter.
I recommend turning a spoon over, and gently pouring the water over the batter so it does not create large divots in the batter. Do not stir!!
Carefully slide the baking dish into the oven and bake for 35-40 minutes. Rotating the pan halfway during baking.
The edges will bubble with the fudgy layer underneath. But if you are concerned, insert a toothpick into the middle of the cake to make sure that the batter itself is cooked through.
Cool on a wire rack and serve while still warm, with ice cream, fresh raspberries, and a sprinkle of powdered sugar.