In a small bowl, whisk together the honey and cornstarch. Stir in the orange blossom water if using. Place the peaches in a large mixing bowl and pour the honey mixture over the fruit. Toss gently to coat, and transfer to an 8-inch-square baking dish.

In a medium bowl, combine the rolled oats, flour, sugar, and cinnamon. Stir in the melted butter and the yogurt, and mix until the mixture turns dough-like. Sprinkle the crumble over the peach mixture in the baking dish, using your fingers to break the dough into crumbley bits.

Place the baking dish in the middle rack in the oven and bake until the topping is golden, about 20-25 minutes. Sprinkle with lemon zest. Enjoy warm, or at room temperature.