1/2 stick (4 tablespoons) unsalted butter
4 firm but ripe pears, preferably Bosc, halved lengthwise and cored
6 tablespoons balsamic vinegar
3/4 cup (3 ounces) walnut halves or pieces, toasted
Finely chopped fresh rosemary, to taste
1/2 cup honey (optional)
Freshly ground black pepper, to taste
Adjust the oven rack to the middle position and preheat the oven to 400 degrees. Have ready a roasting pan or baking dish that will just barely accommodate the pear halves in a single layer (you may have to use 2 baking dishes). Using too large a pan will cause the sauce to scorch.
Place the butter in the pan and place on the middle rack until melted, about 3 minutes. Remove from the oven and arrange the pears, cut-sides down, in the butter. Roast the pears in the middle of the oven until almost tender, about 10 minutes, depending on the ripeness.
Drizzle the vinegar over the pears and roast for 5 more minutes.
Immediately transfer the pears, cut-sides down, to serving plates. Sprinkle with the walnuts and rosemary and spoon some of the juices from the baking dish over the pears. Drizzle pears and cheese (if using) with honey (if using) and sprinkle with pepper. Serve at once.
Blue Cheese: Crumble about 1 ounce over each pear half just prior to serving.
Goat Cheese: Place a spoonful of soft goat cheese next to each pear half just prior to serving. Especially good with honey.
Mascarpone: Place a spoonful next to each pear half just prior to serving. The warmth of the pear will melt the mascarpone slightly so it will mingle with the juices from the baking dish. Especially good with honey.
Mascarpone and Blue Cheese Sauce: In a bowl, combine about 1/2 cup of each and mash together. Spoon over each pear half just prior to serving.
Pecorino: Thinly shave aged Pecorino alongside each pear half just prior to serving.