Preheat oven to 180 degrees Celsius.
Mix oil and sugar until well blended.
Add eggs and vanilla; stir just until blended.
Mix all dry ingredients in a separate bowl.
Stir dry ingredients into the oil/sugar mixture.
Pour into greased 9 x 9 square pan.
Bake for 20 minutes or until sides just starts to pull away from the pan.
Cool completely before cutting.
Note: If you double the recipe, you will need to cook longer than 20 minutes.