Place the chicken breasts in the slow cooker. Pour the jar of salsa verde over them. Add the lime juice, cumin, and salt. Cover and cook on low for 3 hours, or until they are cooked through and have reached an internal temperature of 165 degrees F.
Remove the chicken breasts from the crockpot and shred with two forks on a cutting board. Return the chicken to the crockpot. You can also shred the breasts in the crockpot with tongs or forks.
Prepare the spinach according to package instructions, wrap in a paper towel, and squeeze out any excess moisture. Add the cooked spinach and diced bell pepper to the slow cooker. Mix well and cook on low for another 30 minutes.
Serve in tacos, burrito bowls, salads, nachos, and more.
Notes
There will be a lot of liquid/salsa still in the slow cooker when you shred the chicken. The shredded chicken and vegetables should absorb most of this (it has a ton of flavor!), but if it's too much, you can drain some of it.
Be sure to use at least 1.5 pounds of chicken breast. With less chicken, there tends to be too much spinach.
Store in an airtight container in the fridge for up to 5 days. Reheat in the microwave for 1-2 minutes on high or enjoy cold.
To freeze, transfer to airtight containers or freezer bags, label, and freeze for up to 3 months. Let it thaw in the fridge before eating.