01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt until well blended.
03 - In a large bowl, combine melted butter and sugar. Whisk until smooth. Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
04 - Gradually fold the dry ingredients into the wet mixture until just combined. Do not overmix to maintain fudgy texture.
05 - Fold in chocolate chips and nuts if using. Distribute evenly throughout the batter.
06 - Spread batter evenly into the prepared pan. Bake for 25 minutes, or until a toothpick inserted in the center comes out with moist crumbs.
07 - Allow brownies to cool completely in the pan on a wire rack. This is essential for clean cutting.
08 - Lift brownies out of the pan using parchment paper. Use a heart-shaped cookie cutter to cut out heart shapes. Dust with powdered sugar before serving.