Take a large sheet of tinfoil, spray center area with cooking spray.

Thinly slice potatoes, dice peppers, and onion.

Combine potatoes, peppers, onion, and cheese. Salt and pepper to taste. Mix in the center of the tinfoil.

Tightly close up tinfoil. Try to make it air tight. Right before you seal the last side, pour in the milk.

Cook for an hour and 15 minutes, turning halfway through.