Melt the butter in a large saucepan over medium heat, then add mini marshmallows and stir until melted and smooth, about 5-7 minutes.

Remove from heat and fold in rice crispy cereal until fully coated.

Press the mixture into a greased 9x13-inch baking pan evenly and compactly.

In a microwave-safe bowl, melt the chocolate chips in 30-second intervals, stirring until smooth. Stir in peppermint extract.

Spread the melted chocolate mixture over the pressed rice crispy base.

Sprinkle crushed candy canes over the chocolate layer while it’s still warm and lightly press them down.

Refrigerate the bars for at least 2 hours or until chocolate is set.

Once set, cut into squares and serve, optionally garnishing with extra crushed candy canes.