Spray a 3 quart slow cooker with nonstick cooking spray.

In a bowl, sift together flour, sugar, 4 tablespoons cocoa powder, baking powder and salt.

Then stir in milk, oil and vanilla extract.

Give it all a good stir until combined, then fold in nuts (if using).

Spread batter evenly into your slow cooker.

In a separate bowl, combine brown sugar and remaining 4 tbsp. cocoa powder.

Stir in hot water until smooth.

Pour evenly over batter in slow cooker. DO NOT STIR.

Cover and cook on high setting for 2-2 ½ hours (it took about 2 ½ hours for mine to bake).

To test if it is done, stick a toothpick into the center.

If it comes out clean (with no cake batter hanging on it), then it is done.

Let cake stand, uncovered for 30-40 minutes before serving.