01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper for easy cleanup and to prevent sticking.
02 - Place the zucchini rounds in a large bowl. Drizzle with 2 tablespoons of olive oil, then add the kosher salt and black pepper. Toss thoroughly until all pieces are evenly coated.
03 - Arrange the seasoned zucchini in a single layer on the prepared baking sheet, ensuring pieces do not overlap. Roast for 20 to 25 minutes, flipping halfway through the cooking time, until the slices are golden brown and tender when pierced with a fork.
04 - While the zucchini roasts, heat a dry skillet over medium heat. Add the sesame seeds and toast, stirring frequently to prevent burning, until golden and fragrant, approximately 2 to 3 minutes. Transfer to a bowl to cool completely.
05 - In a small bowl, combine the cooled toasted sesame seeds, lemon zest, lemon juice, chopped parsley, minced garlic, crushed red pepper flakes if using, flaky sea salt, and the remaining 1 tablespoon of olive oil. Mix thoroughly to form a cohesive crunchy topping mixture.
06 - Transfer the roasted zucchini to a serving platter in an even layer. Spoon the lemon sesame crunch topping generously over the zucchini. Serve immediately while warm, or allow to cool to room temperature for serving later.