Cut meat into 1/2-inch pieces. Place in a large nonstick skillet and cook half of the meat in hot oil over medium heat until brown. Transfer meat to a 3 1/2- or 4-quart slow cooker. Add the remaining meat, onion, paprika, and garlic to skillet. Cook until meat is brown and onion is tender. Drain off fat. Remove meat mixture to cooker.
Stir water, squash, parsnips, sweet potato, corn, bouillon granules, salt, and cayenne pepper into meat mixture in cooker. Cover and cook on low-heat setting for 10 to 11 hours or on high-heat setting for 5 to 5 1/2 hours. Just before serving, stir in spinach.