Ready the oven: Gather your ingredients. Preheat the oven to 425°F and generously grease an oven-safe wire rack set over another baking sheet.
Prepare the breading ingredients: Stir together breadcrumbs, grated Parmigiano-Reggiano, ½ teaspoon kosher salt, black pepper, and garlic powder in a shallow dish. Stir together flour and remaining ½ teaspoon kosher salt in a separate shallow dish. Whisk together eggs and milk in a third shallow dish.
Cut zucchini sticks: Cut zucchini into 3- to 4-inch x ½-inch sticks. Working in batches, dredge sticks in flour mixture, dip in egg mixture, and dredge in panko mixture, pressing to coat.
Bake zucchini fries: Arrange sticks in an even layer on a generously greased (with cooking spray) wire rack set on a baking sheet. Bake at 425°F until lightly browned and tender, about 25 minutes. Serve with warmed marinara sauce.
