Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine ground beef, Italian sausage, almond flour, egg, garlic powder, onion powder, Italian seasoning, salt, and black pepper. Mix until well combined.
Using your hands, shape the mixture into meatballs, approximately 1 inch in diameter.
Heat a skillet over medium heat and lightly grease it with cooking oil. Brown the meatballs in batches, cooking for about 5 minutes until they are golden on all sides. Remove the meatballs and set aside.
In the same skillet, pour in the marinara sauce and bring to a gentle simmer. Add the cooked meatballs back to the skillet, ensuring they are coated in the sauce. Cook for an additional 5 minutes.
Transfer the meatball and sauce mixture to a baking dish and sprinkle mozzarella and Parmesan cheese on top.
Bake in the preheated oven for 15-20 minutes or until cheese is bubbly and golden.
Remove from the oven and let it cool for a few minutes before serving.