Preheat oven to 350 deg F.
Line a 9×13 inch heavy pan with foil, then spray foil.
In a large pan over medium heat, melt butter and salt.
Add sugar and cook for 2 min on low heat stirring to dissolve some of the sugar.
Remove from heat and cool until lukewarm.
Using an electric mixer, beat the eggs.
Add the vanilla and butter/sugar mixture.
Beat until smooth. On lowest speed, blend in sour cream.
Prepare the flour, cocoa and baking powder together then sift.
Mix until just combined scraping the sides of the bowl.
Add some toasted walnuts into the mixture and reserve some for topping.
Pour batter into prepared pan or dish and sprinkle nuts evenly.
Bake in 300 degree F oven for 30-35 minutes. Cool pan on a rack.
Then cut into even squares. Store in an airtight container.
Note: Brownie should be risen and lightly cracked. If you’re glazing, glaze the brownies before you cut into even squares.
*Here are the instructions for the brown butter glaze:*
In small saucepan, over medium heat, melt butter.
Immediately add sugar and milk and cook on low heat, stirring until thickened.
Allow to cool slightly to thicken up, then pour evenly over brownies and allow to set until firm before cutting into squares.