Peel potatoes and cut into ¼-inch thick slices and place in boiling water until potatoes are soft.
While the potatoes are cooking, dice the bacon into 1/8-inch pieces and cook in a saute pan until crispy. Add the cabbage. Cook until cabbage becomes soft.
Drain the potatoes. In a mixing bowl, mash potatoes and add butter, half and half, cheese and green onions. Fold in the ale, as well as the bacon and cabbage mixture.