We had the best flavor and texture results with the listed amount of olive oil. The dish doesn't taste/feel oily, and any excess oil from the caramelized shallots gets transferred to the paper towels. However, if you need to reduce the amount of oil, you can (1) line the baking sheets with parchment paper for the cauliflower steaks; just keep in mind that this typically results in less browned cauliflower though. You can also halve the amount of oil in the caramelized shallots and garlic, but to prevent burning, you will need to deglaze the pan with a splash of water every 1 to 2 minutes once the shallots start to brown. Also, the shallots will be tasty but won't get as crisp as they normally do.