Step 1
Start by greasing a large bowl and a 9x13-inch baking dish to keep things from sticking. Pour the puffed wheat cereal into the prepared bowl. In a small saucepan, combine the marshmallows, brown sugar, corn syrup, cocoa powder, and butter. Cook over medium-low heat, stirring often, until everything melts together into a smooth, bubbly chocolate mixture. Take the pan off the heat and stir in the vanilla extract. Pour this chocolatey goodness over the cereal and mix it all up until the cereal is evenly coated. Press the mixture firmly into the greased baking dish and let it sit for about 10 minutes to set. Once it's cool enough, turn it out onto a clean surface and use a serrated knife to cut it into squares—either 12 or 24, depending on how big you want them. Wrap each piece in plastic or store them in an airtight container to keep them fresh.
