2. Make the glaze
In a bowl, mix the melted butter and brown sugar until smooth and glossy. Place the potatoes in a lightly greased 4–6 quart slow cooker, pour the mixture over them, and toss until evenly coated.
3. Cook low and slow
Cover and cook on HIGH for 3–4 hours or LOW for 5–6 hours. Stir once halfway through to keep the glaze from settling and to coat all the potatoes evenly.
4. Thicken the glaze
When the potatoes are fork-tender, slightly open the lid and cook on HIGH for another 20–30 minutes. This allows excess moisture to escape and helps the glaze become thicker and stickier.
5. Finish and serve
Turn the slow cooker to WARM and gently stir the potatoes one last time to coat them in the rich glaze before serving.