Preheat your oven to 400°F.
In a large mixing bowl, combine the ground beef, ricotta cheese, Parmesan cheese, breadcrumbs, egg, minced garlic, oregano, salt, pepper, and parsley. Mix until just combined; do not overmix.
Using your hands, form the mixture into meatballs about 1.5 inches in diameter.
Place the meatballs on a baking sheet lined with parchment paper.
Drizzle a little olive oil over the meatballs for added moisture and flavor.
Bake in the preheated oven for 20-25 minutes, or until the meatballs are cooked through and browned on the outside.
In the last 5 minutes of baking, heat the marinara sauce in a saucepan over medium heat.
Once the meatballs are done, add them to the marinara sauce and let them simmer for a few minutes to absorb the flavors.
Serve hot, garnished with additional parsley if desired.