2 cups unsalted butter, melted and cooled
2 cups granulated sugar
1 1/2 cups brown sugar
1 1/2 teaspoons vanilla extract
6 eggs
1 1/2 cups cocoa powder
2 cups unbleached all-purpose flour
3/4 teaspoon baking soda
1/2 teaspoon salt
1 1/2 cups chopped pecans or walnuts (optional)
Nonstick cooking spray

Preheat oven to 350 degrees F. Spray a 9 x 13-inch pan lightly with cooking spray. Line bottom with parchment paper.

In a mixing bowl with electric mixer, blend melted butter with granulated and brown sugar, then add vanilla extract and eggs. Blend well on slow speed.

In a separate bowl, stir together cocoa, flour, baking soda and salt. Fold into batter and blend well, scraping bottom of mixing bowl to ensure ingredients are evenly combined. Fold in nuts if using.

Pour or spoon into prepared pan. Place pan on a cookie sheet (this protects bottoms from over baking while top bakes.) Bake until done (35-40 minutes). Brownies will be set and slightly firm, but not dry.

Cool, then freeze 1 hour before cutting.

Unmold before cutting. Peel off parchment paper. Cut into large 2 1/2 x 3-inch blocks. Wrap each in wax paper and keep refrigerated or frozen.

To serve for a party, pile brownies on platter and dust with confectioners' sugar.