In a large saucepan, melt the butter and peanut butter over low heat. Stir continuously until smooth and fully combined
Once the butter and peanut butter are melted, add the mini marshmallows to the pan. Stir constantly until the marshmallows are completely melted and the mixture is smooth and glossy
Add the vanilla extract and a small pinch of salt (it really enhances the peanut flavor).
Remove the pot from heat and quickly add the Rice Krispies cereal. Stir gently but thoroughly, making sure every bit of cereal is coated with the peanut butter-marshmallow mixture.
Line an 8×8 or 9×13-inch baking pan with parchment paper. The smaller pan makes thicker, chewier bars; the larger one makes thinner, crispier ones
Transfer the mixture into the prepared pan and gently press it down evenly with a buttered spatula or your hands
If you’re adding toppings, now’s the time! Drizzle melted chocolate on top, sprinkle chopped peanuts, or scatter a few chocolate chips before the mixture fully cools.
Let the bars cool at room temperature for at least 30 minutes before slicing.
