Heat oven to 350 degrees.
In a skillet over medium heat, saute the onions and garlic in olive oil until the onions are softened and slightly yellow, about 5 minutes. Set aside.
In a medium bowl, mix ground turkey, turkey sausage, milk, eggs, Worcestershire sauce, parsley, oregano, salt, red pepper, black pepper and oats until completely combined. Fold in onions and garlic.
Spread mixture in an ungreased 8x8 baking dish. Spread marinara on top.
Bake uncovered for 75 minutes (1 1/4 hours). In the last five minutes spread mozzarella over loaf to melt.
Yields 8 servings