Preheat oven to 375 degrees.

In a mixing bowl, cream together butter and salt. Add vanilla extract and mix to combine.

With your mixer on low, slowly pour in sugar then mix until mixture is creamy, about two minutes.

Stir flour in by hand with a wooden spoon or spatula until a stiff and rather dry dough forms.

Stir in chopped chocolate and walnuts with wooden spoon or spatula.

Press mixture into an ungreased quarter sheet pan (about 9X12), pressing to edges.

Bake for 15-20 minutes, until the top is lightly golden brown.

Remove pan from the oven and allow the cookie brittle to cool completely in the pan.

Once cool, flip pan over onto a larger baking pan and break into irregular-sized pieces. Store in air-tight container.