Ina Garten's 1770 House Meatloaf With Garlic Sauce

Ingredients

• 2 tablespoons good olive oil
• 2 cups chopped spanish onion (1 large)
• 1 + 1/2 cups green pepper or celery, diced small(2 stalks)
• 1 pound ground beef
• 1 pound ground veal
• 1 pound ground pork
• 1 tablespoon chopped fresh flat-leaf parsley
• 1 tablespoon chopped fresh thyme leaves
• 1 tablespoon chopped fresh chives
• 3 extra-large eggs, lightly beaten
• 2/3 cup whole milk
• 2 tablespoons kosher/coarse salt
• 1 tablespoon freshly ground black pepper
• 2 + 1/2 cups panko crumbs
• 3/4 cup good olive oil
• 10 garlic cloves, peeled
• 2 cups chicken stock, preferably homemade
• 3 tablespoons unsalted butter, at room temperature
• kosher salt and freshly ground black pepper