Pear and Red Onion Gratin

1 large red onion
3 to 4 Bosc pears
3 tablespoons extra-virgin olive oil
1 tablespoon finely chopped thyme leaves
1/4 teaspoon salt
Freshly ground black pepper
1 cup Japanese-style panko bread crumbs, preferably whole wheat
1/3 cup freshly grated Parmesan cheese

Have ready a large bowl 3/4 full of ice water and ice cubes, and a lightly greased 8-by-8-inch ovenproof glass baking dish. Place the onion in a strainer and lower the strainer into the ice water bath. Let stand for 20 minutes, then drain and transfer to the baking dish.

Preheat the oven to 400 degrees.

Halve and core the pears and cut into 6 slices each. Add them to the baking dish, along with 1 tablespoon of the olive oil, thyme, salt and pepper to taste, stirring to coat evenly. Cover tightly with heavy-duty aluminum foil and roast for 20 minutes, stirring twice during the cooking time.

Meanwhile, combine the bread crumbs and Parmigiano-Reggiano in a medium bowl and add the remaining 2 tablespoons of oil, stirring to combine. Set aside.

Remove the baking dish from the oven and discard the foil. Sprinkle the bread crumb mixture evenly over the top and roast for 20 to 30 minutes, or until the bread crumbs are well browned. Let cool 10 minutes before serving.