Mix the meatball ingredients: Add 1 pounds ground beef (80/20 blend), 1 large egg, 0.5 white onion, finely diced (yellow or red onion also work), 3 garlic cloves, minced, 1 tablespoons tomato paste, 2 teaspoons Italian seasoning, 0.3 cups grated Parmesan cheese, 0.3 cups flax seed powder (or substitute breadcrumbs), 1 teaspoons salt, and 0.5 teaspoons freshly ground black pepper to a large bowl. Use your hands to combine until fully incorporated.

Form the meatballs: Shape the mixture into about 10 large meatballs using your hands. Place each one on parchment paper as you go.

Bring the sauce to a simmer: Pour 24 ounces marinara sauce of choice (1 jar) into a large skillet. Heat over medium heat until the sauce reaches a gentle simmer.

Simmer covered: Carefully nestle the meatballs into the simmering sauce, spacing evenly. Cover and simmer until cooked through.

Flip and stir: Remove the lid, gently flip each meatball, and stir the sauce to incorporate any separated fat.

Simmer uncovered to thicken: Let the meatballs and sauce continue simmering uncovered to thicken the sauce slightly.

Garnish and serve: Spoon sauce over the meatballs. Top with 2 tablespoons fresh parsley or basil, chopped, for serving and 2 tablespoons extra grated Parmesan cheese, for serving. Serve over pasta or with a side salad.