Place the top oven rack in the center position and pre-heat the oven to 350°F.
Line an 8x8-inch baking pan with parchment paper and spray with non-stick cooking spray. Set aside.
Cream the butter and sugar in a large mixing bowl.
Add the eggs and vanilla and mix until combined.
Add the flour, cocoa powder, and salt to a large bowl and stir to combine. Slowly add the dry ingredients to the wet until just combined. (Do not over mix or the brownies will turn out “cakey”).
Stir the chocolate chips and walnuts into the batter and transfer to the prepared baking pan. Spread into an even layer and transfer to the pre-heated oven.
Bake for 22-26 minutes or until a toothpick inserted into the center comes out clean. Brownies will still be soft and will finish setting while they cool.
While brownies are cooling, whisk together all of the ingredients for the frosting.
Frost brownies and top with walnuts.
Notes
Toasting the walnuts brings out their flavor and gives them a great crunch. Toast the walnuts in a 350 degree oven for 5-10 minutes. You don't want to burn them so start checking them at 5 minutes and then every minute or two thereafter until the walnuts are toasted and you can smell their aroma.
Frosting the brownies is optional, but it adds an extra chocolatey flavor to the brownies.