Yes, you can freeze these rice krispie treats! After the topping has set and you have cut them into squares, just stack them in a single layer in a food storage container that has a tight-fitting lid. If you want to stack a second layer on top, separate the layers with a piece of parchment paper to keep them from sticking together as they freeze. When you want to enjoy a peanut butter rice krispie treat from the freezer, just pull one out and let it thaw at room temperature for about 15 - 20 minutes.