Preheat oven to 350 degrees F.
Spray 9x13" baking dish with cooking spray.
In large bowl combine flour, oats, flax, brewers yeast, brown sugar, baking soda, salt, cinnamon, and pumpkin pie spice.
Stir well to combine.
In medium bowl, whisk together pumpkin puree, eggs, coconut oil, milk, and vanilla.
Add wet ingredients to dry ingredients and stir until just combined.
Fold in chocolate chips.
Pour into prepared baking dish and bake in preheated oven for 38-42 minutes, until slightly golden and toothpick comes out clean from the middle.
Let cool completely.
Cut into bars and enjoy!