Step 1: Prepare the Slow Cooker
Grease the inside of your slow cooker with butter or non-stick spray.
Step 2: Add the Pineapple
Pour the entire can of crushed pineapple, juice included, into the bottom of the slow cooker.
Step 4: Add the Butter
Drizzle the melted butter over the cake mix, spreading as much as possible.
Step 5: Cook
Cover and cook on HIGH for 2–3 hours, or until the top is golden, the edges are bubbly, and the cake is fully set.
Step 6: Serve
Turn off the slow cooker and allow the cake to cool slightly before serving.