Hello gadgetbudgetcook. Yes, you can use olive oil instead of vegetable oil for brownies, but it depends on the type of olive oil you have.
Here are a few important details to keep in mind:
* Extra virgin olive oil has a very strong, fruity, and sometimes peppery flavor that will transfer to your brownies. If your discount bottle is extra virgin, it will definitely alter the traditional chocolate taste.
* Regular or light olive oil has a much more neutral flavor profile and will work well without changing the taste drastically.
* If extra virgin is all you have, you can still use it, but expect a distinct savory or earthy undertone in your baked goods.
I hope this helps you decide what to do with your brownie mix! Let me know if you need any other baking tips.