One highly rated molten chocolate cake recipe using a cake mix is slow-cooker chocolate lava cake from Betty Crocker. The recipe calls for one box of Betty Crocker's SuperMoist triple chocolate fudge cake mix.
To prepare the recipe, coat a 6-quart slow cooker with cooking spray, or line it with parchment paper to prevent the cake from burning. Pour the box of cake mix into a large mixing bowl along with 3 eggs, 1 1/4 cups milk and 1/2 cup vegetable oil, and combine with an electric mixer according to package directions. Pour the batter into the slow cooker, and set aside. Pour a box of instant chocolate pudding and pie filling in a separate mixing bowl, ensuring the package is the four-serving size. Beat the pudding mix with 2 cups milk according to package directions, and pour the mixture over the cake batter.
Sprinkle a 12-ounce bag or 2 cups of chocolate chips over the pudding. Cover the slow cooker, and cook on low heat for two and a half to three hours. The cake is ready once the pudding begins to bubble and the cake is set. Optionally, replace 1/4 cup of the milk in the pudding with chocolate- or coffee-flavored liqueur.