Italian Meatballs in Marinara Sauce

In a medium bowl, combine breadcrumbs and milk, letting the mixture sit for 5 minutes until the breadcrumbs have fully absorbed the milk and become soft.
Add ground beef, ground pork, Parmesan cheese, egg, parsley, minced garlic, salt, and pepper to the breadcrumb mixture, using your hands to gently mix until just combined without overworking the meat.
Form the meat mixture into 1 1/2-inch balls using damp hands, placing them on a parchment-lined baking sheet; you should have approximately 20 meatballs.
Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat, then brown meatballs in batches for 3-4 minutes per side until golden brown on all surfaces.
Pour marinara sauce into the pot, gently nestling all meatballs into the sauce, and bring to a simmer before reducing heat to low.
Cover the pot and simmer gently for 20-25 minutes, until meatballs are cooked through and reach an internal temperature of 165°F when tested with an instant-read thermometer.