Sprinkle a thin layer of the buttery breadcrumb mixture over the bottom of the slow cooker to create a base for the apples.
Add a layer of apple slices over the crumbs, overlapping them slightly. Sprinkle a few spoonfuls of the cinnamon brown sugar mixture over the apples.
Repeat layering: breadcrumbs, then apples, then cinnamon sugar, until all the apples are used. Finish with the remaining buttery breadcrumbs spread evenly over the top to form a full, even layer.
Cover the slow cooker with the lid and cook on LOW for 3 1/2 to 4 1/2 hours, or until the apples are very tender and the edges of the breadcrumb topping look set and golden. (The topping won’t be crispy like an oven crisp but will be golden, buttery, and slightly caramelized around the edges.)
Once done, turn off the slow cooker and let the apple brown betty sit, covered, for 10 to 15 minutes. This resting time helps the juices thicken slightly and the topping firm up a bit.
Cover the slow cooker with the lid and cook on LOW for 3 1/2 to 4 1/2 hours, or until the apples are very tender and the edges of the breadcrumb topping look set and golden. (The topping won’t be crispy like an oven crisp but will be golden, buttery, and slightly caramelized around the edges.)
Once done, turn off the slow cooker and let the apple brown betty sit, covered, for 10 to 15 minutes. This resting time helps the juices thicken slightly and the topping firm up a bit.
For a crunchier top, remove the slow cooker insert when the betty is done and briefly place it (if oven-safe) under the broiler for 2 to 3 minutes, watching closely so it doesn’t burn. You can also swap part of the breadcrumbs for crushed plain graham crackers for a slightly more cookie-like flavor.
Food safety tips: Keep the slow cooker covered while cooking to maintain a safe temperature. If you prep the apples ahead, toss them with a little lemon juice and store covered in the refrigerator; do not leave sliced apples at room temperature for more than 2 hours. Leftovers should be cooled, then stored in an airtight container in the refrigerator and eaten within 3 to 4 days. Reheat gently in the microwave or in the slow cooker on warm until heated through.
