Cocoa brownies

Butter, unsalted	140 grams
Sugar, granulated	250 grams
Cocoa powder, unsweetened	65 grams
Salt	¼ teaspoon
Vanilla	½ teaspoon
Eggs, cold	2 large
Flour, all-purpose	65 grams
Walnut or pecan pieces, optional	75 grams

1. Preheat to 325°F; ensure a rack is in the lower third. 
2. Line the bottom and sides of an 8-by-8-inch square baking pan with parchment paper or foil, leaving overhangs on two opposing sides for handles. 
3. In a medium saucepan, combine the butter, sugar, cocoa, and salt, and heat on lowest stovetop setting. 
4. Stir occasionally, until the butter melts and the mixture is smooth and hot enough you want to remove your finger quickly. 
5. Remove from heat and let cool slightly. 
6. Using a wooden spoon, stir in the vanilla. 
7. Add the eggs one at a time, stirring vigorously after each one, and continue until the batter looks thick and shiny. 
8. Add the flour, and stir until you can no longer see any white, then beat vigorously for 40 strokes with a wooden spoon. 
9. Stir in the nuts, if using. 
10. Spread evenly in the prepared pan. 
11. Bake until a toothpick stuck in the center comes out clean, about 20 to 25 minutes. 
12. Let cool completely on a rack, if you can wait that long (I seldom do).