In a large mixing bowl combine the apples, pears, nectarines, plums, strawberries, and blackberries with the lemon juice and cornstarch and toss to combine. Add 1/2 cup sugar, cloves, nutmeg, and salt and stir well. Butter a deep pie dish or a 9 by 12-inch baking dish with 1/2 tablespoon of the butter. Transfer the fruit mixture to the buttered dish, and dot the top of the fruit mixture with the remaining tablespoon of butter.
Bake the fruit, uncovered, about 30 minutes. Remove from the oven and let cool 15 to 20 minutes before serving.