Peel the onions, cut off the root and opposite side of it, cut it half, and then thinly slice the onions.
Preheat a skillet over medium heat and melt the ghee.
Once the ghee is melted, add the onions and start caramelizing the onions. This will take about an hour or so.
Stir the onions occasionally and deglaze the skillet with a couple tablespoons of beef bone broth to ensure it doesn't dry out. You want all the dry bits and pieces for flavor!
When the onions are caramelized, set aside 1/4 cup for the meatballs.
Add the garlic, thyme, and cassava flour to the onions and stir until well combined. Add the beef bone broth, balsamic vinegar, Dijon mustard, and then bring to a boil, lower the heat, and let the soup simmer.
Preheat oven to 375F. Line a large baking sheet with parchment paper and set aside.
In a mixing bowl, add the ground beef, pork, egg, cassava flour, caramelized onions, kosher salt, garlic powder, parsley, and chives. Mix together until well combined.
Using a medium size cookie scoop, form the meatballs and line them up on the baking sheet. If you don't have a cookie scoop, create golf ball sized meatballs. You should get about 22-24 meatballs.
Bake the meatballs for 15 minutes. Remove the meatballs, add it to the French onion soup, and continue simmering the soup until the meatballs are cooked through. ~10-15 minutes.
Serve the French onion soup meatballs over cauliflower mash and enjoy!
If the soup gets too thick while simmer, add more beef bone broth to thin it out if you want it more soup like and not gravy like.