Pop a 6 quart pan full of popcorn and lift by handfuls into large metal dish pan or roasting pan leaving behind any unpopped kernels. Set aside.

Mix 2 cups light brown sugar, 1/2 cup light corn syrup and 2 sticks butter in 2 quart pot. Bring to a boil and continue boiling 5 minutes, stirring frequently. (Be careful not to scorch.) Remove from heat and add 1/2 teaspoon salt, 1/2 teaspoon baking soda and 1 teaspoon vanilla, stirring constantly as mixture swells and changes color. Stir for about 1 minute until it is no longer swelling and changing color.

Then pour immediately over 6 quarts popped popcorn. Stir gently to coat popcorn completely. If desired, add nuts and stir until they are coated. Put in 250 degree preheated oven and bake 1 hour STIRRING WELL EVERY 15 MINUTES.