My great grandmother's recipe for soft caramels. Her name was Tillie Crumpacker but as children, us great grandkids couldn't pronounce "Crumpacker" so we said "Cracker" and she was "Grandma Cracker" ever since.
Put sugar, syrup and salt into a 6 quart pot. Stir to mix. Then on medium heat, cook and stir constantly until thread stage.
While maintaining constant stirring, add butter.
Very slowly add half and half, while stirring.
Keep stirring and cooking till soft ball stage (234 degrees) then quickly add vanilla and stir into mixture.
Immediately after stirring in the vanilla, pour the caramel into prepared 13x9" pan, DO NOT scrape the bottom of the pot (this caramel usually is over-done and somewhat hard), You may scrape the sides.
Let cool completely.
Use spreading knife to separate the caramel from the sides of the pan, then turn over onto cutting board, slightly twisting the pan (this is why it must be a metal pan), use the knife to separate any caramel that is still sticking to the pan.