Preheat oven to 350 F and line a baking sheet with parchment paper. Mix together dry ingredients (except chocolate chips) in a large bowl. In a small bowl, whisk egg and add in coconut oil. Mix together and add mashed banana, vanilla, and sugar. Blend well. Slowly add liquid mixture into the dry mix, stirring consistently to create batter. Drop batter, one tablespoon at a time, onto parchment paper to create cookies. Bake for 10-12 minutes, until edges are slightly brown. Remove from oven and allow to cool.
While cookies cool, place chocolate chips in a small plastic bag. Heat in microwave, 30 seconds at a time, until the chips melt. Squeeze the liquid chocolate into one corner of the plastic bag. Create a small puncture with a pin or scissor and drizzle chocolate over the cookies. Place cookies in the refrigerator for 30 minutes to allow chocolate to harden. Serve chilled or at room temperature. Store in an airtight container in the refrigerator.