Step 1

Line an 8x8-inch baking sheet with parchment paper, leaving a 2-inch overhang on two sides (which will make it easy to lift the bars out when it's time to slice them).

Step 2

Add the peanut butter and honey to a large heat-safe bowl. Warm in the microwave for 15-30 seconds, or until easy to stir. (This may not be necessary if you keep your peanut butter and honey at room temperature.) Stir together to combine.

Step 3

Add the cereal and vanilla, if using, to the bowl. Stir gently, but thoroughly, using a wooden spoon or spatula. It may take a minute or two to get the mixture evenly coated.

Step 4

Press mixture into the prepared baking pan, gently pressing evenly and into the corners.

Step 5

Chill for at least 20 minutes. Remove from the fridge, lift out using the parchment paper, and slice on a cutting board.

Step 6

Wrap each bar in plastic wrap (optional) and store in an airtight container in the fridge. Serve cold.