Prepare a 9x13-inch baking pan with nonstick cooking spray or, for easier removal for cutting, line the pan with parchment paper. Allow the paper to hang over the sides just a little bit so you can easily pull the bars out.
In a large pot, over medium-low heat, melt the butter.
6 tablespoons butter
Once the butter is melted, add the mini marshmallows and let them cook, while stirring frequently, until they are completely melted and smooth. *Don't cook the marshmallows too long, once they're smooth and melted, take them off they're done. 2 bags (10 oz each) mini marshmallows
Remove the pot from the heat and immediately stir in the peppermint extract and vanilla extract until combined. Work quickly so the mixture stays warm and easy to stir.
1 teaspoon peppermint extract, 1 teaspoon vanilla extract
Add the Rice Krispies cereal and stir gently until thoroughly coated with the marshmallow mixture.
9 cups Rice Krispies cereal
Transfer the mixture to the prepared pan. Lightly spray your hands or spatula with cooking spray, and then press the mixture evenly into the pan without compacting or pressing on it too firmly, which can make the treats hard.
Place the white almond bark in a microwave-safe bowl. Microwave in 30-second bursts, stirring after each one, until fully melted and smooth.
24 ounces white almond bark
Spread the melted almond bark evenly over top of the treats using an offset spatula to cover the entire surface in an oven layer, like you're frosting a cake.
Sprinkle the crushed peppermint candy canes over top.
1/2 cup crushed peppermint candy canes
Let the Krispie treat bars set at room temperature, for about 1 hour, or until the almond bark topping is firm and set.
Lift the treats from the pan using the parchment overhang, then cut into squares, and enjoy!