Preheat oven to 300* and lightly butter your baking pan.
Beat salt,butter and sugar together until light and fluffy.
Dissolve baking soda in the vanilla extract and add to butter/sugar mixture, beating until combined well.
Add flour one cup at a time to the butter/sugar mixture ,beat until combined well.
Gently fold in rice krispies until well incorporated. Drop by 2 tablespoon size mounds onto pans and bake for 15 minutes.
Remove pan from oven and flatten cookies slightly with back of spatula and return to oven making sure to rotate pan( if you are doing 2 pans at once then rotate AND switch pans on racks) and cook for 20-25 minutes more. cool on wire rack which seems best because for some reason they seem to hold heat longer than a regular cookie.
*** NOTE*** DO NOT USE REGULAR SALTED BUTTER. Also these can be sprinkled with sugar before baking...or drizzled with melted chocolate after they are cooled.