Italian Meatloaf

Name: Italian Meatloaf
Ingredients: 4 slices white sandwich bread; 1 small yellow onion; 1 stalk celery; 3 cloves garlic; 1 medium carrot; 1 small bunch fresh parsley; 4 ounces low-moisture mozzarella cheese, shredded (about 1 cup); 1 ounce Parmesan cheese, finely grated (about 1/2 firmly packed cup grated on a Microplane or 1/3 cup store-bought); 1 1/2 pounds lean ground beef (90% lean); 1 pound ground pork; 1 (24-ounce) jar store-bought or homemade marinara sauce (about 3 cups), divided; 1 large egg; 2 teaspoons Worcestershire sauce; 2 teaspoons kosher salt; 1 teaspoon Italian seasoning; 1/2 teaspoon freshly ground black pepper; 1/4 teaspoon red pepper flakes