Spread in layers as listed above, making about 3 layers. Save enough French- fried onion rings to crumble and sprinkle over top about 20 minutes before serving. Add 1/2 cup water and cook on High for 7 to 10 hours or on low 12 to 18 hours. If using frozen green beans, use 4 packages of cut-up green beans. Cook on High 4 to 5 hours or on low 8 to 10 hours.