Preheat oven to 400°F (200°C). In a large bowl, whisk together almond flour, egg, grated onion, garlic, Parmesan, salt, pepper, oregano, and parsley until it forms a wet paste.

Add beef and pork to the bowl. Gently fold with your hands or a spatula just until combined; stop the moment no streaks of meat remain.

With oiled hands, roll the mixture into 20 equal balls (about 1 1/2 inches across) and place them on a parchment-lined baking sheet.

Bake on the middle rack for 18-22 minutes, until an instant-read thermometer reads 160°F (71°C) or the centers show no pink. For extra color, broil for the last minute.

Transfer the hot meatballs to a skillet of warm marinara sauce, toss to coat, and let them sit together for 1-2 minutes. Serve with fresh parsley.