Warm the olive oil in a large Dutch oven over medium-high heat. Add the chopped onion, celery, carrots, garlic, and a sprinkle of red pepper flakes. Cook until the vegetables are softened and fragrant, about 5 minutes.

Incorporate the butter into the mixture, then stir in the dry orzo pasta. Sauté until the orzo turns golden brown, about 1 to 3 minutes.

Pour in the broth, add the Italian seasoning and bay leaf, and bring the mixture to a boil over high heat. Season with salt and black pepper to taste. Reduce the heat and let it simmer for 8 to 10 minutes, or until the orzo is al dente, stirring frequently to prevent sticking.

Mix in the milk and Parmesan cheese, followed by the greens and the lemon juice and zest. Continue to cook for a few minutes until the greens are wilted and the soup is heated through.

Ladle the soup into bowls and garnish with additional Parmesan cheese, a grind of black pepper, and a sprinkle of fresh parsley. Enjoy your warm, comforting orzo lemon soup!