This dough is going to be greasier than the one made with butter. I also found that between batches, the oil would start to separate. I would advise giving the dough a good stir before forming your cookies and baking them in the oven. As for the olive oil, be sure to use extra light because it has a neutral taste and neutral smell. It even says on the label that it can be used for baking. If you use regular olive oil, you might taste it.