Spray 5-quart slow cooker with cooking spray. In 12-inch skillet, cook half of the beef over medium-high heat 5 to 7 minutes, stirring occasionally, until thoroughly cooked; drain. Remove beef from skillet to slow cooker. Repeat with remaining beef. Add onions, garlic, chile, tomato paste, tomatoes, broth, chili powder and cumin to slow cooker; mix well.
Cover; cook on Low heat setting 8 hours. Garnish individual servings with cheese and green onions.