Put a pot (large enough to fit broccoli) of water on to boil. Break broccoli into florets. When the water is boiling, add a handful of kosher salt, and then the broccoli florets. Return to a boil, and cook until florets are just tender. Drain in a colander and set aside.
Just before serving, heat the olive oil on medium high in a large skillet. When the oil is hot, add the butter, as soon as butter foams, add the broccoli, season generously with salt and pepper and cook, tossing just until seasonings are distributed and the broccoli is heated through. Serve.