2 Tbs. plus 1 tsp. canola or olive oil
1 medium yellow onion, chopped
1/2 cup small-diced carrots
1/2 cup coarsely chopped leeks
2 large cloves garlic, finely chopped
4 oz. medium-coarse white bread, such as Italian or French, cut into 2-inch pieces (about 2-1/2 cups)
1 cup whole milk
2 lb. ground beef
2 large eggs
4 Tbs. chopped fresh basil
1/2 tsp. crushed red pepper flakes
1/4 tsp. ground cinnamon
1 Tbs. Worcestershire sauce
Kosher Salt
Freshly ground black pepper
3 Tbs. ketchup
 
Heat 2 Tbs. of the oil in a 10- to 12-inch skillet over medium-low heat. Cook the onion, carrots, leeks, and garlic, stirring frequently, until softened and just beginning to brown, 6 to 8 minutes.
 
Transfer to a large bowl and let cool until warm.
 
In a shallow dish that holds it in a single layer, soak the bread in the milk, flipping once, until soggy but not falling apart, 5 to 10 minutes, depending on the coarseness and freshness of the bread. Lightly squeeze a handful of bread at a time to remove some of the milk (it should be wet but not drenched). Finely chop and add to the bowl with the onion mixture.
 
Position a rack in the center of the oven and heat the oven to 375 degrees F.
 
Add the beef and eggs to the onion mixture. Scatter the basil, red pepper flakes, and cinnamon over the meat, and then sprinkle with the Worcestershire, 2-1/4 tsp. salt, and 1/2 tsp. pepper. Use your hands to gently mix all the ingredients until just combined; try not to compact the mixture as you do this.
 
Heat the remaining 1 tsp. of oil in a small skillet over medium-low heat. Form 1 Tbs. of the meatloaf mixture into a small patty. When the oil is hot, cook the patty on both sides until cooked through, about 5 minutes total. Transfer to a plate and let cool slightly. Taste and adjust the salt, pepper, and other seasonings as needed. Repeat until you're satisfied with the flavor.
 
Line a 9x13-inch baking pan with parchment. Transfer the meatloaf mixture to the baking pan and form into a 10x4-inch rectangular block (it becomes loaf-shaped as it cooks). Spread the ketchup over the top and lightly down the sides of the meatloaf to glaze it.
 
Bake until an instant-read thermometer registers 160 degrees F in the center of the meatloaf, 40 to 55 minutes.
 
Let the meatloaf rest for 10 minutes. Transfer to a cutting board or serving platter with a large spatula and cut into 3/4- to 1-inch-thick slices.