In a small saucepan heat cream and 2 Tbsp. water until steaming hot; remove from heat; set aside.
Place the 1/2 cup water in a 2-quart saucepan; pour sugar and salt in a thin stream in center of pan to form a low mound. Don't stir; use your fingers to pat the sugar mound down until it is entirely moistened. Any sugar touching edges of pan should be below the water line. Cover and cook over medium heat without stirring until sugar is dissolved and syrup looks clear.
Uncover and continue to cook without stirring until syrup begins to color slightly. Swirl pan gently (rather than stirring) if syrup is coloring unevenly. If syrup gets too dark, it will taste bitter. Use a skewer to drop a bead of syrup on a plate from time to time. When a drop of syrup looks amber (about 13 minutes), remove pan from heat. Holding pan away from you, gradually pour in the hot cream mixture. Stir over low heat to blend the caramel into the cream mixture. Simmer for 1 to 2 minutes.
Remove from heat; stir in vanilla. Let cool until slightly thickened (220 degrees F-222 degrees F). Serve warm with Walnut Cake with Caramel Whipped Cream. Or store, tightly covered, in the refrigerator up to a week. Makes 12 servings.