Take the leaves, peeled outer layer, scape bud, and any other garlic scraps into a saucepan with the asparagus ends, Parmesan rind, and water. Place over medium heat, and bring to a simmer. Season with ½ t-spoon kosher salt, and keep it at a simmer for 30 minutes on medium/medium-low. After 30 minutes, strain through a fine mesh sieve lined with cheesecloth—you should have 3 cups left. Pour this back into a pot and put over low heat, covered, to stay warm.