1. Preheat your oven to 350°F (175°C).
2. In a 9x13-inch glass baking dish, melt the 8 tablespoons of butter in the oven for about 5 minutes.
3. In a medium bowl, mix together 1 ¼ cups of sugar, self-rising flour, vanilla extract, and milk until well combined.
4. Once the butter is melted, pour the batter over the butter in the baking dish. Do not stir.
5. In a separate bowl, mix the remaining 1 cup of sugar with the cocoa powder.
6. Sprinkle the cocoa and sugar mixture evenly on top of the batter in the baking dish. Do not stir.
7. Pour the 2 cups of boiling water on top of the cocoa mixture. Do not stir.
8. Bake in the preheated oven for 40-45 minutes, or until the top is golden brown and the cobbler has set.
9. Serve the chocolate cobbler warm with a scoop of ice cream on top.