FOR THE MEATBALLS:
1/2 lb. lean ground beef
1/2 lb. mild Italian sausage
1/2 c. grated parmesan cheese, plus more for garnish
1/4 c. chopped fresh flat-leaf parsley, plus more for garnish
1 large egg
1 garlic clove, finely chopped
1/2 c. panko breadcrumbs
1/2 tsp. kosher salt
1/2 tsp. ground black pepper
Nonstick cooking spray
FOR THE SOUP:
1 tbsp. olive oil
1 c. chopped carrots
1 c. chopped yellow onion
1 c. chopped celery
3 garlic cloves, finely chopped
1 tsp. kosher salt
1 tsp. ground black pepper, plus more for serving
6 c. chicken broth
14 oz. can beef broth
1 c. pearl couscous or small pasta
5 oz. baby spinach
2 tbsp. fresh lemon juice
For the meatballs: Preheat the oven to 450º with the oven rack in the upper third of oven. Line a rimmed baking sheet with heavy duty aluminum foil.
Mix together the beef, sausage, parmesan, parsley, egg, garlic, panko, salt, and pepper in a medium bowl until well combined. Form the mixture into about 40 (1/2-inch wide) meatballs. Lightly spray the baking sheet with nonstick spray and arrange the meatballs in a single layer.
3Bake the meatballs for 6 to 8 minutes or until they are firm to the touch. Increase the heat to broil. Broil the meatballs for 2 to 4 minutes or until browned. Set aside.
For the soup:
Heat the oil in a large stockpot or Dutch oven over medium-high heat. Add the carrots, onion, and celery, and cook for 4 minutes or until the vegetables start to soften. Add the garlic and cook, stirring, for 1 minute.
Gradually stir in the salt, pepper, chicken broth, and beef broth. Bring to a boil. Reduce heat to a gentle simmer, and add the couscous. Cover and cook 8 minutes or until the couscous is just tender.
Add the spinach and cook for 1 minute, until just wilted. Stir in the meatballs and cook 2 minutes or until the meatballs are warmed throughout. Remove the pot from the heat and stir in the lemon juice.
Serve the soup in bowls, and garnish with additional parmesan cheese, chopped parsley, and black pepper.