Prepare the Brownie Base: Preheat your oven to 350°F (175°C) and prepare your brownie mix as per the package instructions. Bake it in a 9-inch springform pan for about 20-25 minutes or until a toothpick inserted in the center comes out clean. Allow the brownie base to cool completely.

Make the Mint Cream Filling: In a large mixing bowl, beat the cream cheese and sour cream until creamy and smooth. In a separate bowl, whip the heavy cream and powdered sugar until stiff peaks form. Carefully fold in the whipped cream and peppermint extract into the cream cheese mixture until you achieve a light and fluffy texture.

Assemble the Cheesecake: Spread the mint cream filling evenly over the cooled brownie base. Smooth the top using a spatula and then refrigerate the cheesecake for at least 4 hours, or preferably overnight for the best results.

Make the Chocolate Topping: To create a luscious chocolate drizzle, melt the semi-sweet chocolate and butter in a heatproof bowl in the microwave, heating in 20-second intervals and stirring until smooth. Allow it to cool slightly before drizzling over the chilled cheesecake.

Garnish & Serve: Finally, decorate with fresh mint leaves and chocolate curls for that elegant touch. Slice this beautiful cheesecake and get ready to savor each mouthful of minty-chocolate bliss!