Make the brownies: Heat oven to 350° F. Generously butter 2 12-cup mini muffin pans. In a medium bowl, whisk together the flour, cocoa, and salt; set aside.
In a medium saucepan, melt the butter and chocolate over low heat. Remove the pan from heat and mix in the sugar and vanilla. Add the eggs and mix until combined. Stir in the flour mixture until just combined (do not overmix).
Spoon the batter into the muffin cups, filling them no more than two-thirds full. Bake until a toothpick inserted in the center of a brownie comes out clean, 20 to 25 minutes. Set the pans on wire racks to cool for 10 minutes, then transfer the brownies to the racks and let cool completely.
Make the ganache: Place the cream and chocolate in a microwave-safe bowl and microwave on high, stirring occasionally, until melted, 1 to 2 minutes. Whisk to combine. Whisk in the peppermint extract. Let cool 10 minutes.
Assemble the brownie bites: Spread the ganache over the cooled brownies and sprinkle with the candies. Place them on a baking sheet and refrigerate until the ganache is firm, at least 1 hour and up to 8 hours.
Storage suggestion: Keep the brownie bites at room temperature in a single layer, covered, up to 3 days.