Prepare the gluten-free brownies and let them cool completely.
In a bowl, whisk together the chocolate pudding mix and milk. Let set until thickened.
Fold the peppermint extract into the whipped topping.
Cut brownies into bite-sized pieces.
In a trifle bowl, layer half of the brownie pieces, then half of the pudding, followed by half of the peppermint whipped topping.
Repeat the layers with the remaining ingredients.
Top with crushed peppermint candies.
Refrigerate until ready to serve.