Grease the bottom and sides of your slow cooker lightly with a bit of the melted butter.
Arrange the lemon slices in an even layer on the bottom of the slow cooker.
Place the cod fillets on top of the lemon slices, making sure they don’t overlap.
In a small bowl, whisk together the remaining melted butter, olive oil, minced garlic, chicken broth, salt, and pepper.
Pour the butter-garlic mixture evenly over the cod fillets, ensuring each piece is coated.
Cover the slow cooker and cook on low for 2–3 hours, or until the cod flakes easily with a fork.
Once cooked, sprinkle the minced parsley over the top for a fresh burst of color and flavor.
Serve the cod fillets with the cooked lemon slices and spoon the flavorful juices from the slow cooker over the top.
Enjoy!