grease the inside of a 4- to 6-quart slow cooker with a small amount of butter to help prevent sticking and encourage those golden edges.
Peel the potatoes and slice them into thin rounds, about 1/8 inch thick, using a sharp knife or mandoline. Place the slices in a large bowl and keep them loosely covered with a clean kitchen towel while you prep the onions so they don’t dry out.
Peel the onions and slice them into thin half-moons. Try
