Preheat your oven to 350°F (175°C). Place the butter into a 9x13-inch baking dish and set it in the oven to melt while the oven heats. Once the butter is melted, carefully remove the dish and set it aside.

In a large bowl, combine 1 1/2 cups granulated sugar, 3 tablespoons unsweetened cocoa powder, 2 cups self-rising flour, 1 cup whole milk, and 2 teaspoons vanilla extract. Stir until the mixture is smooth and well combined.

Spoon the batter over the melted butter in the baking dish. DO NOT STIR—the batter should float on top of the butter.

In a separate bowl, mix together 2 cups granulated sugar and 1/2 cup unsweetened cocoa powder. Sprinkle this mixture evenly over the batter.

Slowly pour 3 cups of boiling water over the sugar and cocoa topping. Again, DO NOT STIR—this is crucial for creating the cobbler’s signature sauce.

Place the baking dish in the oven and bake for 35-40 minutes, or until the top is set and has a slight crust. The bottom will still be a little loose and saucy.

Let the cobbler cool for 15-20 minutes to allow the sauce to thicken slightly before serving. Serve warm with vanilla ice cream if desired.