Add the frozen meatballs and marinara sauce to the crockpot. Pour 1 cup of the broth into the empty marinara jar, put the lid on, and shake to get the rest of the sauce off the sides. Pour it into the crockpot and stir.
Cover and cook on LOW for 4 - 6 hours or HIGH for 2 - 3 hours.
Add the orzo, kale, and remaining 2 cups broth. Give everything a big stir so the orzo is well coated in liquid.
Cover and cook on LOW for 15 - 20 minutes (switch to LOW if you cooked on HIGH), until the orzo is tender and has soaked up most of the liquid.
For a soupier consistency, stir in more broth a little at a time.
Serve in bowls, topped with parmesan if you like.
