or so of the flour mixture evenly over the onions.
Dot a few small pieces of butter (about 1 tablespoon total) over the top of the flour and onions. This helps the top of each layer get that buttery, golden finish as it cooks.
Repeat the layers—potatoes, onions, a light sprinkle of the flour mixture, and small dots of butter—until you’ve used all of the potatoes and onions. Try to finish with a potato layer on top, then dot the remaining butter all over the surface. This top layer is what will get those crispy browned spots and golden edges.
Cover the slow cooker with the lid and cook on HIGH for 3 1/2 to 4 hours or on LOW for 6 to 7 hours, until the potatoes are very tender when pierced with a fork and the onions are soft
