For the buttermilk ranch dipping sauce: In a bowl, combine the buttermilk, mayonnaise, chives, dill, celery salt, garlic powder and onion powder. Mix well. Cover and chill for 1 hour.
For the zucchini fries: Add the flour to a shallow baking dish. In a second baking dish, lightly beat the eggs with 1/2 teaspoon salt and 1/4 teaspoon black pepper. In a third baking dish, combine the panko, Parmesan, garlic powder, 1 teaspoon salt and 1/4 teaspoon pepper; gently crush all the ingredients together with your hands--this will ensure an even coating on the zucchini.
Lightly coat the zucchini sticks in the flour and then dip into egg mixture, coating evenly. Gently shake to remove excess egg and then generously coat the zucchini in the panko mixture. Transfer the breaded zucchini to a baking sheet.
Fill a high-sided skillet with about 1 inch of oil--make sure the oil does not rise more than halfway up the side of the skillet. Heat over medium-high heat. Working in batches to avoid overcrowding, add the zucchini sticks to the pan. Cook until light golden brown, turning once, 2 to 3 minutes. Immediately remove the zucchini to a cooling rack set over a baking sheet. Keep warm in a 175-degree oven until ready to serve.
Serve the zucchini fries with the dipping sauce on side.