Preheat oven to 350ºF.
In a heavy bottom pot bring 3 quarts of water to a boil. Add the 2 tablespoons of kosher salt and add the green beans.
Cook the green beans until just tender, about 8 minutes. Drain immediately and set aside.
Fry the bacon in a heavy bottom skillet. Cook until crispy and set aside.
In the same skillet with all the bacon fat, add the sliced mushrooms and cook for about 8 minutes until they have softened.
Add the garlic and cook for 30 seconds until fragrant.
Sprinkle the flour and stir well. Add the chicken broth and cook for 2 minutes.
Reduce the heat to medium, and add the heavy cream. Add salt and pepper as needed.
Add the green beans to the mushroom sauce and coat them completely.
Transfer the green beans to a baking dish and top with the crispy bacon and shallots.
Bake uncovered for about 20 minutes until bubbly.
Serve and enjoy.