Italian Wedding Soup

Name: Italian Wedding Soup
Ingredients: 3/4 lb. ground chicken; 1/2 lb. chicken sausage, casings removed; 1/2 c. panko bread crumbs; 1/3 c. freshly grated Parmesan, plus more for serving; 2 tsp. dried oregano; 3 cloves garlic, minced; 1 large egg; Kosher salt; Freshly ground black pepper; Pinch of red pepper flakes (optional); 2 tbsp. extra-virgin olive oil, divided; 1/2 medium onion, chopped; 2 medium carrots, peeled and chopped; 2 stalks celery, chopped; 2 tsp. freshly chopped thyme; 8 c. low-sodium chicken broth; 3/4 c. small dry pasta (such as acini di pepe or tubetini); 4 c. baby spinach; 2 tbsp. freshly chopped dill, for garnish; Lemon wedges, for serving