Preheat oven to 350°F (177°C). Line a large cookie sheet with parchment paper or silicone baking mat.
Add peanut butter, syrup and oats into a large mixing bowl. Stir until maple syrup is completely incorporated into the peanut butter and oats are fully coated. Your mixture should resemble a thick cookie dough.
Portion the dough into 1 tbsp pieces (I packed the dough into my tablespoon). Take one piece of dough and roll between palms until it forms a round ball. Place it onto your prepared cookie sheet and then flatten the dough ball until it becomes a round disk (about 1/4 inch thick). You can do this with the back of a metal spoon or the palm of your hand. Space cookies about 1/2 inch apart. The cookies don't spread during baking so you don't need to space them out as much.
Bake cookies for about 9-10 minutes (I baked mine 10 minutes) or until the surfaces look cooked. Let cookies cool completely on the cookie sheet before removing.
Notes
Make sure to use natural peanut butter. This recipe will not work with regular peanut butter.
This recipe works best with pure maple syrup. Other syrups may work but they will likely need a watery consistency like maple syrup. I've tried it with honey and the dough does not thicken the same way.
These cookies are only lightly sweetened. They are similar to biscuit cookies though not quite as firm.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.