What is your favorite three ingredient recipe?

I do all the cooking around here, and while I enjoy the challenge making a full meal from scratch, there are a couple recipes that are easy and quick. Of course, these foods aren’t meals, but more like snacks or treats. My latest one is Pistachio Butter. Pistachios, olive oil and sugar to taste.

Do you have a favorite three-fer recipe? What is it? Where or how did you learn to make it?