In a medium skillet, heat the olive oil and 1 tablespoon of butter over medium heat
Add the green beans and mushrooms. Season with salt and pepper. Cook for 5 minutes.
Add the garlic and remaining butter. Cook for another 5 minutes.
You can cut the green beans if you would like smaller pieces instead of whole beans.
My favorite way to eat them is to blanch the haricot verts first. This keeps a nice crunch and a bright color.