Put one cup of sugar in a heavy cast iron skillet over medium-low heat. As the sugar begins to melt, stir constantly with a wooden or silicon spatula until completely melted and light brown in color. 

Meanwhile, in another large heavy cast iron skillet combine the remaining sugar and cream and bring to a simmer over medium heat.

Add the caramelized sugar to the cream and sugar mixture and stir continuously to combine; cook to firm ball stage, stirring frequently. 

Remove from heat, add the soda, and beat the mixture for 2 minutes. Add the butter and let it sit undisturbed for ten minutes. Add the vanilla and beat the mixture until candy thickens. Fold in the nuts and pour into a buttered pan. Allow the candy to set, and cut into squares.

The candy can also be dropped by spoonfuls onto waxed paper.