Sprinkle the mixture evenly over the squash in the gratin dish.
Sprinkle the cheese evenly over them and add the melted butter.
Season with salt and pepper, then sprinkle evenly with the sugar.
Sprinkle the flour evenly over the vegetables and stir.
Spread in the baking dish and sprinkle evenly with the topping.
Chop the hazelnuts and sprinkle evenly over the top.
Dribble remaining 2 tablespoons oil over top and sprinkle evenly with cheese.
Smooth the top and sprinkle evenly with the cheese.
Sprinkle the cheese evenly over the potatoes, place in the oven and bake for 20 minutes.
Divide chicken among 6 plates, and sprinkle evenly with sesame seeds.