Preheat oven to 350°F (175°C) and grease a small brownie pan (8x8 inch or 20x20 cm) with vegan margarine or oil.
In a medium bowl, sift together flour, cocoa powder, baking soda and salt and set aside. In a large mixing bowl, stir together brown sugar, oil and vanilla. Stir in flour mixture. Add pumpkin and stir just until combined. Fold in chocolate chips, reserving some for the top.
Spread batter in prepared pan and sprinkle with remaining chocolate chips. Bake for about 20 minutes until fine cracks are visible across the top of the brownies. Remove brownies from oven and cool completely in the pan on a wire rack.
Chill brownies before cutting for best results. Pumpkin Brownies stay fresh and moist for several days tightly covered in refrigerator.