In a large mixing bowl, combine the ground beef, eggs, diced onion, parmesan cheese, almond flour, minced garlic, oregano, salt, and pepper. Mix until just combined.
Transfer the mixture to a loaf pan or shape it into a loaf on a baking sheet lined with parchment paper.
Spread the ketchup evenly over the top of the loaf.
Bake for 45–55 minutes, or until the internal temperature reaches 160°F.
Let the meatloaf rest for 10 minutes before slicing and serving.