Preheat your oven to 350°F. Line the bottom of an 8x8 pan with parchment paper spray or with cooking spray.
In a large mixing bowl, add the peanut butter, eggs, honey, and vanilla. Mix to combine. Stir in baking soda, cinnamon, old-fashioned oats, and whole wheat flour until everything is evenly incorporated.
Place batter in the prepared pan and press the mixture into the pan's bottom in an even layer. Bake for 15-17 minutes. If you overcook it, it may get dry. Stick a toothpick into the center; it's done when it comes out clean.
You can stop here or add a little chocolate topping. While bars cool on a wire rack, melt chocolate in the microwave in 30-second intervals, stirring between intervals until completely melted.
Once your chocolate is melted, drizzle it over the top of the bars. Enjoy!
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Notes
You can substitute regular flour for whole wheat if you prefer. The chocolate drizzle is optional, but it makes the bars extra tasty. Refrigerator: To store your oatmeal bars made with peanut butter, layer your bars between waxed paper in an airtight container. Keep in the fridge for up to 5 days.Freezer: You can also flash-freeze them and then freeze them in an airtight container for up to three months.Nutritional information is approximate and was calculated using a recipe nutrition label generator and will vary based on cooking methods and brands of ingredients used.