Preheat oven to 325° F. Carefully line a 9x13" baking pan with foil and spray the foil with cooking spray. Set aside.
In a medium sized saucepan, warm the chocolate and butter over low heat, stirring regularly until both are melted. Once melted set aside.
In a stand mixer or using a hand mixer, whip together the sugar and eggs on medium high speed for 3 minutes. Carefully fold the egg/sugar mixture and vanilla into the chocolate. Fold the flour, salt, and walnuts into the chocolate, just until everything is combined (do not over mix).
Pour batter into prepared baking pan and bake for 35-45 minutes, until the middle is set and a toothpick comes out clean with a few moist crumbs in the center. Serve warm or refrigerate and serve cold.
Notes
- These brownies are best when prepared with nuts, but if cannot make them with nuts (allergies or personal preference), substitute the 1 1/2 cup of nuts with 1 1/2 cups of chopped baking chocolate or chocolate chips.