Thick slices of herb-flecked meatloaf make an excellent sandwich filling for kids and adults alike. Recipe courtesy of Jennifer Aaronson, culinary director of Martha & Marley Spoon.
Preheat oven to 375 degrees. In a large bowl, whisk together egg and 1/4 cup ketchup.
In a food processor, pulse onion, celery, and carrot until finely minced, scraping down sides of bowl to ensure even chopping. Add vegetables to ketchup mixture, along with meat, panko, mustard, Worcestershire, herbs,2 1/2 teaspoons salt, and 1/2 teaspoon pepper. Mix well with your hands until thoroughly combined.
On a rimmed baking sheet lined with parchment, firmly pat mixture into a long, narrow loaf (4 by 12 by 1 1/2 inches). Coat top and sides with remaining 1/2 cup ketchup. Bake until browned and a thermometer inserted into thickest part reaches 165 degrees, 45 to 55 minutes. Let cool at least 30 minutes, then cut into thick slices. Serve on buns, with lettuce, mayonnaise, and pickles.