In a 10-inch skillet heat oil over medium-high heat. Brown veal shanks or beef ribs, half at a time, in hot oil. Transfer the meat to a 3-1/2- to 4-quart crockery cooker, reserving drippings in skillet. Sprinkle the meat with pepper.
Add onion and garlic to skillet. Add more oil if necessary. Reduce heat to medium; cook until onion is tender, stirring occasionally. Add chicken broth, scraping bottom of the pan to loosen any browned bits.
Transfer the onion mixture with juices to the crockery cooker. Add potatoes. Cover and cook on the low-heat setting for 8 to 9 hours or on high-heat setting for 4 to 4-1/2 hours or until meat is nearly tender.
Add squash, Brussels sprouts, and horseradish to cooker, rearranging so vegetables are in cooking liquid. Stir together cornstarch and water; stir into mixture in cooker. Increase heat to high. Cook, covered, for 45 to 60 minutes or until vegetables are just tender. Transfer meat and vegetables to a serving platter. Sprinkle with parsley, if desired. Makes 4 servings.