Slice the zucchini tops and bottoms off. Slice into ¼-inch pieces. You can either slice on the bias or straight across.
Using a large shallow bowl, add the milk and eggs. Whisk until completely incorporated and uniform in color (pale yellow).
Place one cup of flour into a gallon Ziploc bag. Working in small batches, place the sliced zucchini into the bag. Shake to coat the slices with flour, then remove with a slotted spoon making sure to knock off any excess flour.
Add the flour-coated zucchini into the egg mixture, and toss to coat completely.
Add the remaining 2 cups of flour, breadcrumbs, grated parmesan, Italian seasoning, kosher salt, and cracked black pepper to a gallon-size Ziploc bag. Shake to combine the dry ingredients. Set it aside.
Add the oil to a 10-inch skillet over high heat and heat to 325°F. A candy/oil thermometer will help with gauging when your oil is ready to fry.
While the oil is heating, remove the zucchini from the egg mixture using a slotted spoon and add to the Ziploc with the dry coating mixture. Shake to coat and make sure the pieces are separated, so all sides get coated. It is best to do this in batches. You can dust the bottom of a baking dish with the dry coating to help with keeping the coated zucchini dry.
Once the oil reaches temperature, carefully add a small batch to the oil. Lower the heat if the oil temperature goes above 345-350°F. Cook for 1-1½ minutes, flip and continue cooking the other side for 1 to 1½ minutes until golden. Remove the zucchini from the oil to a baking dish lined with a paper towel. Repeat until all the zucchini is cooked. Eat immediately.