Bring large pot of boiling water to a boil; add a big pincg of salt and all the green beans. Cook for about 5 minutes, the beans should still be crisp, they will be cooked more in the oven. Drain them, spread out on paper towel to dry, and set aside. Butter a baking dish large enough to hold the green beans with 1 tablespoons butter and set aside.
Heat oven to 375 degrees.
Tear bread into 2" pieces, put ina bowl and add t tablespoons chives, 1 tablespoons thyme, 1 tablespoons rosemary, 2 tablespoons Parmesan, and 3 tablespoons olive oil. Stir well to coat and spread onto a baking sheet. Bake just until the bread starts to turn golden, about 10 minutes. Remove from the oven and set aside.
Meanwhile, melt the remaining butter and olive oil in a large skillet over medium heat. Add the mushrooms and shallots, season with salt and pepper, and cook until the mushrooms have released their liquid, about 10 minutes. Pour in the heavy cream, add the remaining thym and chives, and cook for another 5 minutes. Add the green beans and stir well. Put the green beans mixture into the prepared baking dish, top with the croutons, and sprinkle on the remaining Parmesan. Bake until everything is hot and bubbling, about 20-25 minutes.