Spring Green Soup with Chicken

Name: Spring Green Soup with Chicken
Ingredients: 2 tablespoons extra-virgin olive oil; 1 pound chicken tenders; 2 medium leeks, white and light green parts only, thinly sliced; 1 medium yellow onion, chopped; 2 stalks celery, chopped; 2 cloves garlic, minced; 4 cups low-sodium chicken broth; ¾ teaspoon salt; ¾ teaspoon ground pepper, plus more for serving; 1 bunch asparagus, cut into 1-inch pieces; 1 (5 ounce) package baby spinach; 1 cup packed fresh parsley leaves; ¼ cup grated Parmesan cheese, plus more for serving