Slice the zucchini lengthwise into ¼-inch thick slices using a mandolin for uniform cuts.

Beat the egg in a bowl until fully combined and slightly frothy.

Mix together panko breadcrumbs, grated Parmesan cheese, kosher salt, black pepper, and garlic powder in a separate bowl.

Preheat the Blackstone griddle on medium heat for about 5 minutes, adding oil to prevent sticking.

Dip each zucchini slice in the beaten egg then coat it in the panko mixture, ensuring it's evenly covered.

Arrange coated zucchini slices on the griddle, leaving space in between each slice, and cook for 2-3 minutes on each side until golden brown.

Transfer cooked zucchini slices to a serving platter and serve warm with ranch or Caesar dressing for dipping.