Spray the inside of a 6 quart slow cooker with non-stick spray.
In a medium size mixing bowl, whisk together flour, cocoa powder, sugar, baking powder, and salt. Set aside.
In a separate bowl, whisk together milk, oil and vanilla. Add this wet mixture to the dry ingredients. Stir just until mixed. Fold in chocolate chips.
Pour cake batter into the crock pot and smooth out the top. Place a dishtowel over the crockpot, held in place by the crock pot lid. This helps to keep moisture from building up on the surface of the cake.
Cook at high power for 1.5 hours or until set.
Spoon servings out of the crockpot and top with things like hot fudge, chocolate syrup and ice cream, or dust with powdered sugar, whipped cream and berries!