- 1½ cup brown sugar (unpacked, divided)
- 1 cup flour
- ¼ cup + 3 tablespoons unsweetened cocoa powder (divided)
- 2 teaspoons baking powder
- 1 teaspoon salt
- ½ cup milk
- 4 tablespoons melted butter (divided)
- 2 teaspoons vanilla (divided)
- ¼ cup white sugar (divided)
- 1¾ cups boiling water
- ¼ cup light corn syrup
- ½ cup peanut butter
- Mix together 1 cup brown sugar, flour, 3 tablespoons cocoa, baking powder, and salt.
- Stir in milk, 2 tablespoons melted butter, and 1 teaspoon vanilla. Spread in a greased crockpot on high setting.
- Whisk ½ cup brown sugar, 2 tablespoons white sugar, and ¼ cup cocoa powder together. Sprinkle over the batter in the crockpot. Pour boiling water over the top – do not stir! Let cook for 2 hours.
- For peanut butter sauce: melt corn syrup, 2 tablespoons white sugar, 1 teaspoon vanilla, and 2 tablespoons melted butter over medium low heat. When sugar has dissolved, add peanut butter and stir until melted. Keep warm until serving.