In a large skillet over medium heat, add half of your olive oil and sauté half of the diced yellow onion until it's translucent and fragrant—about five minutes. Pour in your marinara sauce and let it simmer while you prepare the meatballs.

In a large bowl, combine ricotta cheese, minced garlic, dried herbs (basil, oregano, parsley), remaining onion, minced garlic cloves, whisked egg, half and half, breadcrumbs, Parmesan cheese, chopped parsley, Italian seasoning, mustard powder, salt, pepper, ground chuck, and ground beef. Use your hands to gently mix until just combined; be careful not to overmix.

With clean hands or using an ice cream scoop for uniformity, shape your mixture into meatballs about one inch in diameter. Place them on a baking sheet lined with parchment paper.

For stovetop cooking: Gently add the formed meatballs into your simmering marinara sauce and cover. Let them cook for about 30 minutes on low heat. For baking: Preheat your oven to 400°F (200°C) and bake for around 25 minutes until golden brown. For Crock Pot method: Place meatballs directly into your sauce in the Crock Pot and let it cook on low for approximately four hours.

Once cooked through and beautifully browned or bubbling in sauce depending on your method of choice—garnish with additional chopped parsley before serving!