Bake potatoes at 400° for about 1 hour or until done. Cut a thin slice off the top of each potato and discard. Carefully scoop out pulp while leaving shell intact. In a mixing bowl, mash pulp with milk, sour cream, onion salt and pepper until smooth. Fold in asparagus. Stuff shells; place in an ungreased shallow baking dish. Sprinkle with cheese and bacon. Return to the oven for 20-25 minutes or until heated through.