4 tablespoons (56 grams) butter
6 tablespoons (98 grams) peanut butter (creamy or crunchy)
5 ounces (140 grams) marshmallows (mini or regular, I usually buy this brand)
1 teaspoon (5 ml) vanilla extract
4 cups (120 grams) honey nut o’s cereal
Line an 8-inch (20-cm) square pan with a sheet of parchment paper long enough to hang over the sides.
Add the butter, marshmallows, and peanut butter to a 4-quart deep pot. Cook over medium heat until the mixture begins to melt. Add the vanilla. Using a rubber spatula, stir until the marshmallows are mostly melted, and the peanut butter is dissolved. Remove from the heat.
Add the cereal to the pot, and stir with the spatula, quickly, until the cereal is well coated. Scrape the mixture into the prepared pan. Use the spatula to press it out to the edges of the pan, and into an even layer. Let cool for about 30 minutes, until it’s set. Using the ends of the parchment paper as handles, lift the treats from the pan. Cut into 16 squares. Store in a tin, in a cool dry place, for up to 3 days.