MELT butter in a small saucepan over medium heat. Add sugar. Bring to a gentle boil, whisking occasionally. Cook for 3 min. Stir in vanilla and salt until dissolved. Remove from heat and let stand 1 min. Whisk in 1/2 cup cream until sauce is smooth.
BEAT remaining 1 1/2 cups 35% cream in a large bowl until soft peaks form, 2 to 3 min. Add 1 cup cooled rich salted-caramel sauce and beat until combined. Scrape into a 9 x 5-in. loaf pan. Cover surface with parchment paper. Freeze 4 to 5 hours. Let stand 15 min before serving.