Prepare the zucchini:

Grate the zucchini using a cheese grater and measure out 1 heaping cup. Place the grated zucchini in a clean paper towel or cheesecloth and firmly squeeze to remove all excess moisture. Transfer the prepared zucchini to a large mixing bowl, discarding the liquid.

Assemble the meatballs:

To the bowl with zucchini, add ground chicken, breadcrumbs, egg, basil pesto, lemon zest, Italian seasoning, garlic powder, red pepper flakes (if using), kosher salt, and black pepper. Gently mix with clean hands until all ingredients are thoroughly combined. Shape the mixture into 16 evenly sized meatballs, resembling the size of golf balls. If needed, refrigerate the formed meatballs on a parchment-lined tray for up to 24 hours before cooking.

Cook the meatballs:

In a large, oven-safe skillet, heat 1–2 tablespoons of olive oil over medium-high heat. Sear the meatballs, turning occasionally, until browned on all sides, about 6 minutes. The meatballs do not need to be fully cooked at this stage. Remove them from the skillet and set aside.

Sauté the mushrooms:

In the same skillet, add 1 tablespoon of olive oil and the chopped mushrooms. Season with salt and pepper, then cook over medium heat, stirring occasionally, until the mushrooms release their liquid and begin to brown, approximately 5–8 minutes. Stir in the minced garlic and cook for an additional minute until aromatic.

Prepare the orzo:

Gradually pour the chicken broth into the skillet, scraping the bottom to deglaze and incorporate any flavorful bits. Stir in the milk, basil pesto, lemon zest, lemon juice, kosher salt, and Italian seasoning. Add the orzo pasta, ensuring it is evenly distributed.

Bake the dish:

Nestle the browned meatballs into the orzo mixture and transfer the skillet to a preheated oven at 400°F. Bake for 10–12 minutes, or until the orzo is tender and the meatballs are fully cooked. Sprinkle the top with mozzarella cheese and return to the oven for an additional 5 minutes, or until the cheese is melted and lightly golden.

Garnish and serve:

Remove the skillet from the oven and garnish with fresh basil, grated Parmesan cheese, and a sprinkle of red pepper flakes, if desired. Serve warm and enjoy a nourishing, well-rounded meal.