Step 1: Preheat Oven

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease and line a 9×13-inch baking pan with parchment paper for easy removal.

Step 2: Prepare the Brownie Batter

1. Melt Butter: In a medium saucepan, melt the butter over low heat. Remove from heat and let it cool slightly.
2. Mix Sugar and Eggs: In a large mixing bowl, combine the melted butter and granulated sugar. Mix well. Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.
3. Combine Dry Ingredients: In another bowl, whisk together the flour, cocoa powder, salt, and baking powder.
4. Combine Wet and Dry: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.
5. Add Chocolate Chips and Nuts: If using, fold in the chocolate chips and chopped nuts until evenly distributed.

Step 3: Bake the Brownies

1. Pour Batter: Pour the brownie batter into the prepared baking pan and spread it evenly.
2. Bake: Bake in the preheated oven for 25–30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).

Step 4: Cool and Serve

1. Cool: Allow the brownies to cool in the pan for about 10–15 minutes, then lift them out using the parchment paper and transfer to a wire rack to cool completely.
2. Slice and Enjoy: Once cooled, slice into squares and serve.