Heat until just melted, stirring constantly. Once the mixture comes together and the oil has melted, immediately remove from the heat.
Stir in the cocoa and salt, mixing to combine.
25 grams cocoa powder, 1/4 teaspoon sea salt
Add the puffed wheat and stir, using a spatula, until fully coated in the peanut butter mixture.
200 grams puffed wheat
Turn the puffed wheat mixture out into the prepared baking dish and press into as even a layer as possible.
Place the dish into the freezer and chill for at least ten minutes (or refrigerate for 30 minutes), then lift it out of the dish with the parchment paper and slice into bars.
Store the bars in an airtight container at room temperature for a couple of days, or freeze up to three months. I prefer to keep these in the refrigerator for best texture.
Notes
* In the step-by-step images, you'll see that it's a rectangular dish. That's because the recipe as shot there was doubled, but it was too much for a single batch - it's been reduced now for a more manageable amount.