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 combined.
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.
06 - Spread batter evenly into the prepared pan, smoothing the top with a spatula.
07 - Bake for 25 minutes, or until a toothpick inserted in the center comes out with moist crumbs attached.
08 - Allow brownies to cool completely in the pan on a wire rack.
09 - Lift brownies out of the pan using parchment paper. Use a heart-shaped cookie cutter to cut out heart brownies.
10 - Dust with powdered sugar before serving.