Preheat oven to 325 degrees. Line a 9?9 inch baking dish with foil or parchment paper and set aside.

Melt the butter in a medium saucepan over medium-low heat. Add the sugar, cocoa powder, and salt, and stir well to combine. Continue to cook, stirring occasionally until the mixture is very warm to the touch. Remove from heat and stir in the peppermint extract, then allow to cool for 5-10 minutes.

Add the eggs one at a time, beating vigorously after each addition. Stir in the flour just until incorporated, then stir in the chocolate chips and peppermint crunch, reserving some for the top of the brownies.

Pour the batter into the prepared pan and spread evenly, then top with the reserved chocolate chips and peppermint crunch.

Bake for 20-25 minutes, or until the center is puffed and a toothpick inserted into the center comes out with just a few moist crumbs. Cool completely on a wire rack.