1/4 cup thick yogurt (preferably Greek), sour cream, or crème fraîche
2 teaspoons honey plus additional (optional) for drizzling
Directions
Put oven rack in middle position and preheat oven to 450°F. Oil a baking sheet.
Halve apples lengthwise and remove core with a melon-ball cutter or a paring knife. Melt butter in a 10-inch heavy ovenproof skillet over moderate heat and sprinkle with 1/2 tablespoon sugar. Arrange apple halves, cut sides down, on sugar and cook, undisturbed, until sugar begins to caramelize, 3 to 5 minutes. Transfer skillet to oven and bake apples until tender, about 15 minutes.
While apples are baking, cook remaining 1/4 cup sugar with salt in a dry 7- to 8-inch heavy skillet over moderately high heat, undisturbed, until sugar begins to melt, about 2 minutes. Continue to cook, stirring occasionally with a fork, until sugar is melted into a deep golden caramel, 1 to 2 minutes more. Remove from heat. Add walnuts, stirring to coat, then pour onto baking sheet and cool 10 minutes. Break nuts into small pieces if necessary.
Stir together yogurt and 2 teaspoons honey.
Serve apples, cut sides up, topped with yogurt and nuts. Drizzle with additional honey if desired.
