01 - Preheat oven to 350°F. Line a 9x9 inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large bowl, whisk melted butter with sugar until smooth. Add eggs and vanilla extract, mixing until fully blended.
03 - Sift in flour, cocoa powder, and salt. Stir gently until just combined without overmixing. Spread three-quarters of the batter evenly into the prepared pan.
04 - In a separate bowl, beat cream cheese and sugar until smooth. Add egg and peppermint extract; mix until creamy. If desired, incorporate red food coloring and fold in crushed peppermint candies.
05 - Spoon dollops of the cheesecake mixture over the brownie layer. Add remaining brownie batter in spoonfuls on top. Use a knife or skewer to gently swirl both batters for a marbled effect.
06 - Bake for 33 to 36 minutes until center is set and a toothpick inserted comes out with a few moist crumbs.
07 - Allow bars to cool completely in the pan. Refrigerate for at least 2 hours before lifting out and slicing. Garnish with additional crushed peppermint candies before serving.