Spray slow cooker with cooking spray. Place onions in bottom and pour beef broth over the top.
In a small bowl combine chipotles, adobo, olive oil, honey, cumin, salt, and paprika. Place brisket on top of onions; spread chipotle mixture on top. Cover and cook until brisket is tender, about 8 hours.
Remove brisket and slice or shred. Return to slow cooker and toss with onions and beef broth.