1. Preheat oven to 350°F (175°C). Grease an 8×8″ metal pan (glass may over-bake edges).
2. Melt butter in a saucepan (or microwave). Stir in sugar until smooth. Cool 2 mins.
3. Whisk in eggs one at a time, then vanilla.
4. Sift in flour, cocoa, and salt. Stir just until combined—don’t overmix! Fold in nuts if using.
5. Pour into pan; spread evenly. Bake 20–23 mins—edges set, center still slightly soft (a toothpick should have moist crumbs, not wet batter).
6. Cool completely in pan before slicing (they firm up as they cool!).

PREP TIME & NUTRITION :
Prep Time: 10 mins, Cook Time: 22 mins, Total Time: 32 mins (+ cooling), Servings: 16
Calories: 125, Net Carbs: 17g, Fats: 6g, Protein: 2g
(For keto version: swap sugar for ¾ cup powdered erythritol + ¼ tsp stevia, use almond/coconut flour blend—net carbs: 2g/serving)