Blanch the green beans:

1. Fill a 5-6 quart stockpot halfway with water. Bring it to a boil. Meanwhile, create an ice bath by filling a large bowl with ice water.
2. Working in batches, put the green beans into the boiling water and cook for 2 minutes. Use a kitchen timer to ensure they don’t overcook.
3. Immediately remove the beans from the boiling water and put them in the ice bath. Let the beans sit in the ice bath for 2 minutes, then remove them from the water into a colander to strain. As the beans cool, preheat the oven to 375F.

Prepare the batch of homemade cream of mushroom soup:

1. In a medium stockpot, melt 2 Tbsp butter over medium heat.
2. Add 1 cup mushrooms, 1 tsp thyme, 1 clove garlic (minced), 2 tsp salt, ½ tsp pepper, and 1 tsp onion powder. Cook until the mushrooms start to soften, about 5-7 minutes.
3. Add 2 Tbsp flour to the pot and stir to coat. Let the flour cook for about 1 minute, stirring occasionally.
4. Add ½ cup milk and ½ cup beef broth and whisk well to incorporate the flour into the liquid.
5. Bring the mixture to a boil and whisk well until the soup is very thick, anywhere from 2-5 minutes.
6. Taste the soup (careful, it will be hot) and add additional salt if needed.

Prepare the topping:

1. Combine all of the topping ingredients in a small bowl. When the oven is preheated, place the blanched green beans in a casserole dish. (I recommend an 8″x8″ dish for one pound of beans and a 9″ x 13″ dish for 2 pounds of beans.)
2. Pour the prepared homemade cream of mushroom soup over the top of the beans.
3. Sprinkle the topping evenly over the top and bake for 25-30 minutes, or until the top is golden and bubbly.