Prepare an 8x8 pan, lined with wax paper

Add all the ingredients except the vanilla to a heavy bottom pot

Set heat to medium and clip a candy thermometer to the pot

When everything is melted stir once and watch thermometer closely after it reaches 235 degrees

When it reaches 248 degrees remove from heat, wait until the bubbling subsides a bit and then add vanilla

Stir well

Pour into prepared pan

After 20 minutes sprinkle with sea salt if using

Leave at room temperature for about 4 hours until completely cooled

Remove caramel from pan

Cut into small pieces and wrap in wax paper