Combine all seasonings in a small bowl, reserving half of the rosemary.
Baste the chicken with unsalted butter and olive oil and then cover with seasonings.
Add half of the onion, lemons, and rosemary to the inner cavity of the chicken.
Roll up three small lemon-sized balls of foil and place in the bottom of the slow cooker. Place half of lemons and onion with water into the bottom of the slow cooker.
Add remaining rosemary to the top of the chicken.
Cover and cook on low for 7-8 hours, or high for 4-5 hours.
Keep this meal healthy by serving the chicken with salad or garlic flavored cauliflower rice.
Store leftovers in an airtight container for up to 3 days.
**Nutrition facts are based on my best estimation for this recipe. They may not be accurate depending on what brands you use or modifications you might make to the recipe. For most accurate calculations, I recommend using a nutrition calculator with the exact brands and measurements you use with the recipe.