Preheat oven to 350 degrees. Line baking sheet with parchment paper or silicone baking mat and set aside.
In a large bowl, cream butter and sugar. Stir in egg and vanilla. Scrape sides and whip until light and fluffy. Stir in all dry ingredients until just incorporated. Scrape sides and mix again briefly. Stir chocolate chips into the dough.
Spread a thin layer onto prepared baking sheets and bake approximately 12 minutes. Cool cookie bars completely before slicing. Store in an airtight container for up to 3 days.
Serve with ice cream...and chocolate sauce for good measure.