Mix together the salt, baking soda, rolled oats, and flour and then gradually add to the creamed mixture, beating well after each addition.
Make Filling:
In a medium saucepan, mix together filling ingredients except for walnuts.
Over medium-low heat and stirring often, cook until chocolate is completely melted.
Add walnuts if using and stir to mix; set aside.
In an ungreased 10 × 15 × 1-inch baking pan (or you can use a 9 × 13-inch pan, but you may need to bake the revel bars for 1-3 minutes longer) spread about ⅔ of the dough evenly across the bottom.
Using a rubber spatula, scrape the filling onto the dough in the pan, spreading evenly.
Dot the top with the remaining dough.
Bake at 350° for about 25 minutes or until top is golden.
