Preheat the oven to 350°F. Line an 8″x8″ baking dish with parchment paper and set aside.
Whisk together wet ingredients: In a medium bowl, whisk together the peanut butter, maple syrup, egg, melted butter, and vanilla extract.
Add the dry ingredients: To the wet ingredients, add the flour, baking soda, and salt. Fold in gently with a spatula, then fold in the chocolate chips.
Bake: Pour the batter into the lined baking dish and spread to level the top. Sprinkle the top with more chocolate chips, if desired. Bake for 29-34 minutes, or until a toothpick comes out clean. Allow to cool completely before slicing into bars.