Melt spread in a medium saucepan over medium heat. Add mushrooms and onion; cook, stirring frequently, for 10 minutes. Stir in flour; cook and stir for 5 minutes more. Slowly add stock and bring mixture to a boil; reduce heat and simmer for 10 minutes. Stir in half & half and season with salt and pepper; set aside.
Preheat oven to 350 degrees F. Cook beans in boiling water for 5 minutes. Drain well then add to mushroom sauce; toss to coat with mixture. Transfer to an 11 x 7-inch baking dish.
Stir together all topping ingredients until well blended and sprinkle around the edge of the beans.