Put diced peaches in a saucepan with peach nectar; simmer for about 5 minutes, until peaches are tender. In a 2- to 2 1/2-quart lightly buttered baking dish or rectangular baking pan, arrange bread crumbs. Drizzle bread crumbs with 2 tablespoons melted butter then toss with the peach mixture. In a bowl, whisk eggs with granulated sugar, milk, and 1 teaspoon vanilla. Pour mixture over bread crumbs, stirring slightly to distribute milk mixture evenly. Bake at 325° for 1 hour to 1 hour and 15 minutes, until set in center. A larger more shallow pan will take less time than a deeper pan. Brown Sugar Vanilla Sauce: Combine all ingredients in a saucepan over medium heat. bring to a boil, stirring frequently. Reduce to medium-low and let boil for 5 minutes. Remove from heat. Sauce will thicken as it cools.