Spray the bowl of a 6 quart slow cooker with nonstick cooking spray then set it aside.
To a large mixing bowl add the cake mix, milk, oil, and eggs. Using an electric hand mixer blend everything together until the mixture's smooth and evenly combined, scraping the sides of the bowl as needed.
1 13.25 oz box super moist chocolate fudge cake mix, 1 cup milk, 1/2 cup canola oil, 3 eggs
Transfer the batter to the prepared slow cooker and spread out in a mostly even layer.
In another mixing bowl add the pudding mix and the COLD milk. Whisk them together, just until evenly combined and thickened.
1 3.9 oz box instant chocolate pudding mix, 2 cups cold milk
Pour the pudding mixture slowly into the slow cooker overtop of the cake mix. Do NOT mix them.
Spread a clean dish towel over the bowl of the slow cooker then add the lid to cover keeping the towel in place.
Cook on LOW for 3 - 3 1/2 hours, until the cake's set at the edges.
Turn off the slow cooker, remove the lid, and let the cake cool for 30 - 45 minutes.
Spoon into bowls, serve the lava cake warm, and enjoy!