At the 2.5-hour mark, lift the lid and gently press the center of the dessert with the back of a spoon. If it feels completely liquid, replace the lid and continue cooking. If it yields with gentle pressure but feels set and cooked through rather than raw, it is ready. Remember that the texture you are aiming for is soft and gooey, not firm — this is meant to be scooped from the dish, not sliced cleanly.
Turn off the slow cooker and remove the lid. Allow the dessert to cool for 5 to 10 minutes with the lid off before serving. This brief resting period lets the temperature come down enough to be comfortable to eat and allows the texture to settle slightly from its hottest, most liquid state.
To serve, use a large spoon or ice cream scoop to portion the warm cookie dessert into individual bowls. Add a generous scoop of cold vanilla ice cream immediately before bringing each bowl to the table, so the ice cream begins melting the moment it hits the warm cookie base. The contrast of hot and cold, gooey and creamy, rich chocolate and clean vanilla, is genuinely what this dessert is all about.
