Heat the olive oil in a skillet over medium heat. Add the lamb pieces and brown them on all sides for about 5 minutes.
Transfer the browned lamb to the slow cooker. Add the diced onion, sliced carrots, and minced garlic.
Stir in the cumin, coriander, cinnamon, paprika, salt, and black pepper.
Pour in the diced tomatoes with their juices and the chicken broth. Add the rinsed lentils and stir everything to combine.
Cover and cook on low for 7 to 8 hours until the lamb is tender and the lentils are soft.
Taste and adjust salt or pepper if needed. Serve hot with the chopped parsley sprinkled on top.