Preheat the oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a mixing bowl, combine the flour, oats, baking soda, salt, and brown sugar.

In another bowl, whisk together the melted butter, egg, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined.

Fold in the chocolate chips.

Spread the mixture evenly into the prepared baking pan.

Bake for 25 minutes or until the edges are golden brown.

Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Cut into bars and serve.