Take out a large bowl and use measuring spoons to measure out and place the first 6 ingredients (almond flour through the egg) in it. Use a fork or small whisk to mix everything together until well combined and there are little to no lumps. Set aside.

Peel then roughly chop the onion using a cutting board and large sharp knife. Place the onion into a food processor and process until diced (or finely chop with a knife).

Thaw the frozen spinach in a microwave, either according to package directions or by placing in a microwave safe container, covering with lid or plate, then microwaving in 30 second increments until defrosted. Once it's no longer frozen, place it in several paper towels and squeeze the excess water out over the sink. You may need to do this several times to get the bulk of the water out.

Remove the spinach from the paper towel & place it in the food processor in clumps, with the onion. Use the food processor to mix the two together until well combined. Remove the spinach and onion mixture and place it into several paper towels. Squeeze any excess moisture out again, then remove the spinach and onion from the paper towels and place it in the bowl with the egg mixture.

Grab the cutting board and line it with either parchment or wax paper, or plastic wrap. Set it to the side of the bowl. Place the ground beef in the bowl and use your hands to mix everything together well.

Separate the meat mixture into 4 equal portions. Grab one of the portions and use your hands to form it into a patty roughly a quarter inch thick. Place it onto the covered cutting board and do the same with the remaining 3 portions of meat mixture.

Heat the grill to 350-375 degrees F and, once it's come to temperature, place the patties on the grill. Cook for 5 minutes with the lid closed, then open the lid and use a metal spatula to flip the patties. Brush 1 tablespoon of ketchup onto each patty with a basting brush and cook for another 5 minutes. Check the internal temperature and cook for another 3 to 5 until the internal temperature of the patties reaches 160 degrees F. Remove from the grill and serve.