1 cup flour
2 teaspoons baking powder
6 tablespoons butter
2 ounces semisweet chocolate (or 1/3 cup chocolate chips
2/3 plus 1/3 cup sugar
3 tablespoons plus 1/3 cup cocoa
1 tablespoon vanilla
1/4 teaspoon salt
1/3 cup milk
1 egg yolk
1/3 cup brown sugar
1 1/2 cups hot water
Whipped cream or ice cream
Coat the inside of a slow cooker with cooking spray. Whisk together the flour and baking powder in a medium bowl and set aside. In a large bowl, melt the butter and chocolate in the microwave or over a pan of simmering water and mix well.
Whisk in the 2/3 cup of sugar, 3 tablespoons cocoa, vanilla, salt, milk and egg yolk. Add the flour mixture and stir until throughly mixed.
Pour the batter into the slow cooker and spread it evenly. In a medium bowl, whisk together the remaining sugar, coca, and hot water until the sugar is dissolved. Pour the mixture over the batter in the slow cooker. Cover and cook on high for 1 or 2 hours, depending on the size of the crock pot.
Even when done, the cake will be very moist and floating on a layer of molten chocolate, but you'll know it's ready when nearly all of the cake is set and the edges begin to pull away from the sides of the pot. (As you check, try not to let the condensed steam from the lid drip onto the cake.)
When it's done, turn off power and remove the lid. Let it cool for 25 and minutes, then serve it in bowls topped with whipped cream or ice cream. Makes 6 to 8 servings.