1 cup + 3/4 cup packed brown sugar, divided
1 cup flour
1/4 cup + 3 tbsp unsweetened baking cocoa, divided
2 tsp baking powder
1/2 tsp salt
1/2 cup milk
2 tbsps butter, melted
1/2 tsp vanilla
1 3/4 cups boiling water
Combine the 1 cup of brown sugar, flour, 3 tablespoons of cocoa, baking powder and salt in a mixing bowl until well blended. Stir in the milk, butter, and vanilla. Spread the mixture over the bottom of a 3 1/2-quart crockpot or slow cooker.
In a separate bowl, mix the 3/4 cup of brown sugar and the 1/4 cup cup cocoa. Sprinkle the mixture evenly over the mixture in the cooker. DO NOT STIR.
Pour the boiling water over the ingredients in the cooker. Again, DO NOT STIR.
Place lid on cooker and cook on high 2 to 3 hours or until a wooden toothpick inserted in the center comes out clean.
Serve cake warm topped with ice cream or whipped cream, if desired.