Heat the olive oil in a large skillet over medium-high heat on the stove.
Add the sliced onions to the skillet, and cook until they begin to brown and soften.
Remove the onions from the skillet and set aside.
In a mixing bowl, combine the ground beef, pork rind crumbs, egg, french onion soup mix, 2 oz. of the shredded gruyere cheese as well as salt and pepper to taste. Mix together well with your hands until well combined.
Form the meat mixture into 30 evenly sized meatballs.
Place the meatballs in the heated skillet on the stove, and cook, turning to brown evenly until completely cooked through.
Remove the meatballs from the skillet when finished.
Add the beef broth to the skillet, and scrape the bottom to loosen any bits.
Whisk the heavy whipping cream into the skillet until well blended.
Place the onions and meatballs back into the skillet, and toss to coat.
Sprinkle the remaining Gruyere cheese on the meatballs and broil in the oven for 60-90 seconds, or until cheese is melty and bubbly.