Combine all ingredients except vanilla and nuts in a large saucepan.
Cook over low to medium heat, while stirring constantly, until the caramel has reached a warm golden brown color and has reached the 244º F on a candy thermometer. I start checking the candy using the cold water method (drizzle a little bit of candy into a cup of very cold water, and check the consistency) at about 230 degrees. If you don't have a candy thermometer, you can make it using this method alone. Just look for the candy to be soft and chewy, to hold it's shape, but not runny or too hard.
Remove from the heat, add vanilla extract, and beat until creamy with a wooden spoon. Stir in nuts, if you decided to add them.
Pour into a buttered 9x13 glass baking dish. Let sit until the caramel has cooled enough to be handled.
Flip the caramel out onto the counter or plastic cutting board. I like to use kitchen scissors to cut it into pieces about 1 inch wide by 2 inches long. Roll the candy up into a piece of wax paper that's wide enough to twist shut on both sides.