Melt butter in a large saucepan over med-high heat. Cook leeks & carrots for 5 minutes, stirring occasionally. Add 4 cups of water, potatoes and granules and bring to a boil. Cover, reduce heat to medium and simmer for 25-35 minutes, stirring occasionally. Stir in pasta sauce and simmer for another 5-6 minutes or until heated thru. Season with salt and pepper to taste if desired. remove from heat and stir in chives.