Start by making the star of the dish, the meatballs. Combine ground chicken, Italian seasoning, Dijon mustard, Parmesan, salt, and pepper in a large bowl. Use your hands to mix everything just until combined. Roll the mixture into evenly-sized meatballs, about a tablespoon each, and place them directly in the crockpot. Adding a drizzle of olive oil here can help prevent sticking.
Pour the white wine into the crockpot, allowing the liquid to partly submerge the meatballs. Add the quartered onion and a whole trimmed head of garlic. Set your slow cooker to low and cook for 3-4 hours or, if you’re short on time, cook on high for 1-2 hours. The slow cooking allows the flavors to meld while keeping the meatballs moist.
Once the meatballs are cooked, transfer them along with the roasted garlic onto a baking sheet. Broil these for 2-3 minutes at high heat with some butter and a sprig of rosemary. This step adds a golden crispness to the exterior while enhancing the buttery garlic flavor.
Turn the heat on your crockpot to high. Stir the dry orzo directly into the flavorful broth left in the crockpot. Add 1 cup of water if the liquid level seems low. Cover and cook the orzo for about 20 minutes or until it’s tender. Once cooked, mix in the baby spinach, sun-dried tomatoes, and heavy cream. Stir until the ingredients are evenly incorporated and the orzo becomes creamy.
Toss the broiled meatballs back into the slow cooker with the creamy orzo mixture. Serve hot, drizzling the leftover garlic butter from the baking sheet over individual portions.