Caramelize the Onions: Melt butter in a skillet over low heat, add sliced onions, and sprinkle with salt. Stir occasionally and let them cook slow and low for about 20 minutes until golden brown.
Prepare the Meat Mixture: In a large bowl, combine hamburger meat, ground pork, pork rinds, egg, and seasonings. Add half of the caramelized onions and mix everything thoroughly.
Shape & Bake the Meatloaf: Line a baking sheet with parchment paper and shape the meat mixture into a loaf. Bake at 350°F for 40-50 minutes, until the internal temperature reaches 160°F.
Add Cheese & Caramelized Onions: Once the meatloaf is cooked, top it with shredded Gruyère cheese and the remaining onions. Place it back in the oven for 5 minutes to let the cheese melt.
Finish with a Crunchy Topping: Sprinkle French Fried Onions on top for a crispy, flavorful finish. Let the meatloaf rest for 10 minutes before slicing to lock in the juices.