Mix beef, onion, egg, soup mix, oats, and 2 tablespoons catsup in a bowl. Divide into 2 equal balls. Flatten one of the balls on a sheet of aluminum foil. Squirt the flattened meat with catsup and mustard to within 1/2 inch of the edge. Place pickle slices on the meat and top with cheese.
Flatten the other ball of meat and place on top of the first section. Pinch edges shut. Cover the entire thing with the foil.
Take 2 pieces of foil about 18 inches long and fold lengthwise till they're about 2-3 inches wide. These will be handles. Criss-cross them in the crock pot. Place the foil package on top.
Cook on low about 6 hours.
Notes: If you don't like too much salt, cut the amount of soup mix in half. Also, you may want to soak the oatmeal in milk or broth to make the meatloaf moister.