Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper or aluminum foil for easy cleanup.

In a skillet over medium heat, add a tablespoon of extra virgin olive oil. Once shimmering, add diced yellow onion and chopped celery. Sauté for about 7 minutes until soft and golden brown.

In a large mixing bowl, combine lean ground beef and turkey with the sautéed onion and celery mixture. Add chopped parsley, fresh thyme, eggs, fat-free milk, kosher salt, and raw quick oats. Mix gently until just combined.

Shape the mixture into a long loaf or divide into two smaller loaves and place on the prepared baking sheet.

Bake for about 50 minutes or until a meat thermometer inserted into the center reads 160°F (71°C). Let it rest for 10 minutes.

In a saucepan, whisk together salted beef broth, thyme, and flour over medium heat. Bring to a boil, then reduce heat and let simmer for 5-7 minutes until thickened.

Slice the rested meatloaf and serve with the homemade brown gravy ladled over the top.