Crunchy cereal, rich chocolate, and creamy peanut butter combine for delicious dessert.
Line an 8×8” Square Baking Dish with 2 perpendicular pieces of plastic wrap with a few inches hanging over the edges.
In a large Stainless Clad Frying Pan, toast the puffed rice cereal over medium heat until darkly golden and fragrant, about 3 minutes. Transfer to a food processor and grind until broken up like fine bread crumbs. Alternatively, place the cereal in a 1-gallon plastic bag and use a Rolling Pin to crush by hand. Transfer to a large bowl, add the confectioners’ sugar and salt, and whisk together, breaking up any large clumps.
In a Butter Warmer over medium heat, warm the coconut oil or butter until melted. Remove from heat and add 250g (1 cup) peanut butter to the melted oil and whisk together until shiny and smooth. Pour the peanut butter mixture into the bowl with the sugar and crumbs and use your hands (truly the best tool!) to squeeze and fold together until big crumbs form.
Distribute the crumbs around the plastic-lined Baking Dish and press down firmly, filling in all gaps to form a solid layer. Use the flat bottom of a Drinking Glass or measuring cup to finish smoothing and evening out in small circular motions.
Fill a medium Saucepan with 1–2 inches water. Set a heat-safe bowl on top of the Saucepan and place over medium heat until the water comes to a simmer. Add the chocolate to the bowl and allow to melt, stirring frequently, until smooth. Add the remaining 45g (3 Tbsp.) of peanut butter to the melted chocolate and stir to combine. Remove from heat.
Pour the chocolate/peanut butter mixture over the flattened rice cereal layer and, using a butter knife or small offset spatula, spread it into a smooth layer corner to corner. Top with a generous amount of flaky salt.
Transfer to the freezer uncovered for 40 minutes, or until firm to the touch.
Use the plastic overhang to lift the bars out of the pan and onto a cutting board. Tug to remove the plastic wrap from beneath and toss. Let sit at room temperature for 10 minutes to soften.
Use a Chef Knife to score the top at 1-inch intervals all the way across. Slice into eight 1 × 8-inch strips. Set one strip at a time in front of you lengthwise and slice at a 45-degree angle in 11⁄2-inch lengths to form diamonds.
Serve out of the fridge or freezer! The bars can be wrapped and refrigerated for 1 week or frozen for 1 month.