Place potatoes and water in a microwave safe bowl.

Cover and microwave on high for 2 to 3 minutes or until almost tender.

Meanwhile, in a small skillet, cook bacon over medium heat until partially cooked but not crisp.

Remove bacon to paper towels to drain.

Drain potatoes.

On a greased double thickness of heavy duty aluminum foil (about 18 inches square or so), layer half of the potatoes, bacon, onion, cheese and butter.

Repeat layers.

Fold foil around potato mixture and seal tightly.

Grill, covered, over medium heat for 12 to 14 minutes or until potatoes are tender and cheese is melted.

Carefully open foil away from your face to allow steam to escape.