Here's how I put it together. I sliced up some green peppers, and sauteed them in a little EVOO and butter, just till they were done. Sliced up some Onions, sauteed them with a little more EVOO and butter, just til they were translucent and then added sliced Mushrooms. And a little more butter, giggle. Sauteed them all together for a few minutes.
The olive oil is good for you anyway and keeps the butter from browning or burning as easily.