Preheat Oven: 350°F (175°C). Line baking sheet with parchment paper.
Mix Sugars & Butter: Stir melted butter, granulated sugar, and brown sugar until smooth.
Add Eggs & Vanilla: Beat in eggs one at a time, then stir in vanilla extract.
Combine Dry Ingredients: Sift flour, cocoa powder, baking powder, and salt.
Blend Wet & Dry: Gradually fold dry ingredients into wet mixture until just combined.
Add Chocolate Chips & Nuts: Fold in chocolate chips and optional nuts.
Scoop Dough: Drop tablespoon-sized portions onto baking sheet, spaced 2 inches apart.
Bake: 12–15 mins. Edges set, centers soft.
Cool: 5 mins on sheet, then transfer to wire rack.
Serve & Enjoy: Perfect with milk, coffee, or as cookie sandwiches.