01 - Preheat oven to 350°F. Grease 24-cup mini muffin tin or line with paper liners.
02 - Melt butter and chopped chocolate in heatproof bowl over simmering water, stirring until smooth. Cool slightly.
03 - Whisk sugar, eggs, vanilla extract, and peppermint extract into chocolate mixture until well combined.
04 - Sift flour, cocoa powder, and salt into batter. Fold gently until just combined, avoiding overmixing.
05 - Distribute batter evenly among muffin cups, filling 3/4 full. Bake 12-15 minutes until tops are set and toothpick comes out with moist crumbs.
06 - Let cool in tin 5 minutes, then transfer to wire rack to cool completely.
07 - Heat cream in small saucepan until steaming. Pour over chopped chocolate, let stand 1 minute. Add peppermint extract and stir until glossy.
08 - Spoon or pipe ganache onto cooled brownies. Garnish with mint leaves or chocolate shavings. Let set before serving.