Preheat oven to 350°F. Line an 8-inch square pan with parchment paper or greased foil. Set aside.
In a large bowl, whisk together all the dry ingredients: oats, oat flour, flaxseed, cinnamon and salt.
In a medium bowl, whisk together all the wet ingredients: coconut oil, peanut butter, maple syrup, coconut sugar and vanilla.
Pour the wet mixture over the dry mixture. Using a rubber spatula, stir and fold until well mixed. Fold in chocolate chips and peanuts, if using.
Pour this mixture into the prepared baking pan. Using the rubber spatula, spread into an even, tightly-packed layer. Optionally, press chocolate chips into the top of the bars.
Bake for 16-22 minutes, until golden brown on top. Mine took 20 minutes. Place baking pan on a cooling rack, allowing to cool for 30 minutes. Pinch the edges of parchment/foil and lift bars onto the rack to continue cooling completely (about 1-2 hours). Slice into 16 bars. Enjoy!