Begin by lining your 9x9-inch baking dish with parchment paper. This will make it easier to lift the bars out later. Leave some overhang on the sides so you can easily pull them out once they are set.
In a large mixing bowl, combine the old fashioned rolled oats and a generous pinch of salt. Stir them together until they are well mixed. If you are using any optional mix-ins like chia seeds or raisins, add them in at this stage.
In a separate bowl, mix together the creamy peanut butter and honey until smooth and well combined. You can microwave the mixture for about 20-30 seconds if you find it too thick; this will make it easier to stir.
Pour the peanut butter and honey mixture over the dry ingredients. Using a spatula or wooden spoon, stir everything together until the oats are evenly coated. Make sure there are no dry patches, as this will ensure that your bars hold together well.
Transfer the oat mixture into your prepared baking dish. Using your hands or the back of a spatula, press the mixture down firmly and evenly. The more compact it is, the better the bars will hold together.
Once your mixture is pressed into the dish, place it in the refrigerator for at least 2 hours to set. If you're in a hurry, you can speed up the process by placing it in the freezer for about 30 minutes.
After the mixture has set, remove it from the baking dish using the parchment overhang. Place it on a cutting board and cut it into bars or squares, depending on your preference. Store any leftovers in an airtight container for future snacking!
