- Preheat the oven to 176°C or 350°F 
- Heat the olive oil in a large (12-inch) sauté pan over medium heat. 
- Add the onion and  celery and cook for 5 to 7 minutes, stirring occasionally, until the onion is translucent but not browned. 
- Set aside to cool slightly. 
- Place the beef, veal, pork, parsley, thyme, chives, eggs, milk, salt, and pepper in a large mixing bowl. 
- Put the panko in a food processor to obtain a finely ground breadcrumb mix. 
- Add the onion mixture and the panko to the meat mixture. 
- Gently toss the mixture together with your hands, making sure it’s combined but not compacted. 
- Place a piece of parchment paper on a sheet pan. 
- Pat the meat into a flat rectangle and then press the sides in until it forms a cylinder down the middle of the pan (this will ensure no air pockets). 
- Bake for 40 to 50 minutes or check the internal heat to be around 155°F to 160°F. 
- Remove from the oven and allow to rest for 10 minutes. 
- Slice and serve hot with the Garlic Sauce.