In a medium-sized bowl, combine all the meatball ingredients: ground beef, ground pork, salt, pepper, dried parsley, egg, Parmigiano Reggiano, and breadcrumbs. (Take note that you might not need the entire 1/2 cup of breadcrumbs.)
Take a tablespoon of the meatball mix and start forming the meatballs with your hands -- this recipe typically makes 25 meatballs.
When almost finished forming the meatballs, place a pan over medium-high heat.
Add oil, and once ready, gently add the meatballs to start browning them --- this will be in batches.
Set browned meatballs aside and cover with aluminum foil.
Preheat oven to 200°C (375°F).
Carefully remove some of the oil left in the skillet, leave only about 2 to 3 tablespoons of oil.
Add garlic into the skillet and cook until fragrant.
Add tomato sauce, dried oregano, dried basil, sugar, and season with salt and pepper.
Cover with a lid and bring to a boil.
Adjust heat to medium-low and simmer for 10 minutes.
Add the meatballs and mix.
Add remaining Parmigiano Reggiano and the grated mozzarella.
Place skillet in the lower part of the oven for 25 minutes.
Turn the oven off but keep the skillet inside for 5 more minutes.
Take baked meatballs in tomato sauce out of the oven and serve.