Heat the oven to 375°F. Line a rimmed baking sheet with aluminum foil, and top it with a cooling rack. Spray with cooking spray and set aside.
Mix all of the above ingredients (less Marinara Sauce) in a large bowl until well combined. The mixture will be fairly moist but should hold together when formed into a ball.
Scoop the mixture out and roll into balls (I opted to make 9 large ones) and place them on the prepared baking sheet. Bake in the oven until the internal temperature reaches 165°F. For my large meatballs, this took about 30ish minutes.
Serve with your favorite pasta and sauce, and top it all off with cheese. Enjoy!