For caramel topping, combine sugar, water and salt in medium saucepan over medium high heat. Stir sugar and salt until fully saturated with water. Without stirring, allow sugar mixture to cook at medium high heat for 6-8 minutes, or until mixture has a deep amber color. Remove from heat and add heavy cream and butter. Be careful, mixture will steam and bubble up. If caramel seizes, return to heat and continue stirring until smooth. Serve warm, drizzled over pie slices. If caramel cools and solidifies, reheat in microwave in microwave safe container on HIGH for 30 second intervals, stirring in between each.