Drizzle half of the melted butter slowly and evenly over the noodles and cabbage, making sure to moisten as much of the surface as you can. Sprinkle with about half of the black pepper.

Repeat the layering with the remaining cabbage, then the remaining noodles on top. Finish by drizzling the rest of the melted butter over everything and sprinkling with the remaining black pepper.
Cover the slow cooker with the lid and cook on HIGH for 2 1/2 to 3 hours, or on LOW for 4 to 5 hours. Do not lift the lid for at least the first 2 hours so the steam can build and help soften the cabbage and noodles.
After about 2 1/2 hours on HIGH (or 4 hours on LOW), gently open the lid and use a large spoon or tongs to carefully toss the cabbage and noodles together. The cabbage should be very tender and starting to caramelize around the edges, and the noodles should be soft and glossy with butter.
If the noodles are not yet fully tender, cover and continue cooking in 20-minute increments, checking and gently tossing each time, until the noodles are melt-in-your-mouth soft and the cabbage is silky. Taste and add a bit more black pepper if you like a stronger flavor.
Once everything is tender and coated in the rich golden butter sauce, switch the slow cooker to WARM. Serve the cabbage noodles straight from the crock, making sure to scoop from the bottom so each serving gets plenty of buttery cabbage and noodles together.
For a little more depth without adding extra ingredients, brown the butter on the stovetop before pouring it over the cabbage and noodles; it will give the dish a nutty, almost roasted flavor while still keeping to the same four basics. If your slow cooker tends to run hot and you’re worried about the noodles getting too soft, start checking a bit earlier and stir very gently to avoid breaking them up. You can also adjust the pepper to your family’s taste—some of my relatives like a heavy hand with it, which really brings out that traditional Amish-style simplicity. Leftovers reheat nicely in a skillet over low heat; if they seem dry, add a spoonful of water and a small pat of butter to bring back the glossy sauce. For those who enjoy a little texture, let the finished dish sit on WARM with the lid slightly ajar for 10 to 15 minutes to allow a few edges to get a touch more caramelized without drying out the whole batch.