How to Make It
Fill a large bowl with ice water. In a large saucepan of salted boiling water, cook the haricots verts until crisp-tender, about 3 minutes. Drain the beans and let cool in the ice bath; drain and pat dry.
In a large skillet, melt the butter in the olive oil. Add the scallions and cook over moderate heat, stirring, until softened, about 1 minute. Add the morels and season with salt and pepper. Cook over moderately high heat, stirring occasionally, until softened, 5 minutes. Add the haricots verts and cook, tossing, until hot, about 3 minutes. Fold in the chervil and season with salt and pepper. Transfer the beans and morels to a platter and serve.