How to Make It
Preheat the oven to 425° and line the bottom of a roasting pan with parchment paper. In a bowl, soak the bread crumbs in the milk.
In a large skillet, heat the olive oil until shimmering. Add the onion, carrots, celery, garlic and a generous pinch each of salt and pepper and cook over moderate heat, stirring occasionally, until the vegetables are very soft and golden, about 15 minutes. Scrape the vegetables into a large bowl and let cool. Add the tomato paste, eggs, milk-soaked bread crumbs, ground fennel, oregano, celery seeds, crushed red pepper, 2 teaspoons of salt and 1/2 teaspoon of black pepper and stir to form a paste. Using your hands, gently work in the ground beef until combined; do not overmix.
Transfer the meat mixture to the roasting pan and shape it into an oval loaf about 10 inches long. Bake the meat loaf for 50 to 60 minutes, until browned and an instant-read thermometer inserted in the center registers 150°. Let the meat loaf rest for 15 minutes, then cut into thick slices and serve.