Prepare Grilled Peaches; set aside. In a small bowl, whisk together sour cream and 1 tablespoon light-brown sugar.
Spoon mixture over peaches; sprinkle with crushed amaretti cookies.
Choose fruit with a fragrant aroma and flesh that yields a bit when pressed gently. If a peach has cuts or tan spots, or is rock-hard or mushy, don't buy it. Color has more to do with variety than ripeness. Peaches that are tinged green, however, are usually underripe. For the best flavor, look for locally grown, tree-ripened peaches.