Melt the chocolate chips, peanut butter, and salt together. You can do this in a microwave, or in a double boiler by adding an inch of water to a small saucepan and placing a heat-safe bowl on top of the pot. Bring the water to a boil, and gently stir the chocolate chips, peanut butter, and salt together until they are smoothy melted.
Place the rice cereal in a large bowl. Pour the melted chocolate mixture into the rice cereal and stir well, until evenly coated.
Lightly grease a 9-by-5-inch loaf pan and press a piece of parchment paper into the bottom of the pan. (The oil will hold the parchment paper in place.) Transfer the crunch bar mixture into the pan, and smooth the top with a spatula. Place the pan on a flat surface in the freezer to chill until firm, about 1 hour.
When the chocolate feels firm to the touch, you can use the parchment paper to lift the bars out of the pan. Use a sharp knife to slice the chocolate into 1-inch bars. You can make "fun size" bars by slicing the chocolate down the center, as well. (See photos for reference.)
These crunch bars are best kept in an airtight container in the fridge, for up to 2 weeks. When you use an all-natural peanut butter, they will become softer when left at room temperature for too long. You can also freeze these for up to 3 months, if you'd like to store them longer.
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Notes
Nutrition information is for 1 "fun size" bar, assuming you get 18 bars from the batch and use semi-sweet chocolate chips. This information is automatically calculated, and is just an estimate, not a guarantee.For a gluten-free dessert, be sure to use a rice cereal that is labeled "gluten-free." Rice Krispies are not currently gluten-free because they contain malt, but Whole Foods, Barabara's brand, and Cascadian Farms make a gluten-free version.For a lower-sugar treat, use a darker chocolate.For a vegan dessert, be sure to check the label on your chocolate chips to make sure they are dairy-free. Many brands naturally are!