Heat canola oil in a large skillet over medium heat. Season chicken with salt and pepper, to taste. Add chicken to the skillet and cook until golden, about 4-5 minutes.
Place chicken into a 6-qt slow cooker. Stir in chicken stock, onion, carrots, celery, garlic, thyme, rosemary and bay leaf; season with salt and pepper, to taste.
Cover and cook on low heat for 5-6 hours. Uncover and stir in pasta; cover and cook on high heat for an additional 30 minutes, or until tender.
Stir in spinach until wilted. Stir in lemon juice; season with salt and pepper, to taste.