6 tablespoons unsalted butter, cut into chunks
4 ounces semisweet or bittersweet chocolate, coarsely broken or chopped
1/4 cup finely crushed peppermint pinwheel hard candies, plus 1 tablespoon more for garnish
2/3 cup granulated sugar
2 1/2 tablespoons unsweetened natural (non-alkalized) cocoa powder or Dutch-processed cocoa
Powder, sifted after measuring, if lumpy
2 large eggs, at room temperature
1/4 teaspoon peppermint extract
3 or 4 drops peppermint, optional
1/4 teaspoon salt
2/3 cup unbleached all-purpose white flour
1/2 cup chopped semisweet or bittersweet chocolate
Baking Preliminaries: Position rack in the middle of the oven; preheat to 350°F. Line an 8-inch square baking pan with aluminum foil, allowing it to overhang on two opposite sides. Coat the foil with nonstick spray.
Melt the butter in a heavy medium saucepan over very low heat, stirring occasionally, until fluid. Add the chocolate and crushed candy and stir constantly until completely melted and smoothly incorporated.
Immediately remove from the heat; stir in the sugar and cocoa powder until evenly incorporated. Set aside until cooled to barely warm (if the mixture is too warm, it will cook the eggs).
Whisk the eggs, extract, oil of peppermint (if using), and salt into the cooled chocolate mixture until very smooth and glossy. Stir the flour into the mixture just until well blended.
Turn out the batter into the foil-lined pan, spreading into an even layer, then smoothing out the top. Bake, middle rack, until a toothpick inserted in the center comes out clean, 24 to 28 minutes.
Continue checking until just barely baked through. Immediately sprinkle some fi ne peppermint shards over top, if desired. Bake 1 minute longer, then let the pan cool on the rack.
For easiest cutting, refrigerate the brownies until chilled and firm. Lift them to a cutting board using the foil. Gently peel off and discard the foil. Trim off the edges all the way around, then cut into quarters in both directions to make 16 brownies.