Green Bean Mushroom Casserole

1. Preheat oven to 450 F. Fill a large bowl with ice water and set aside.
2. Bring a large pot of water to a boil. Salt the boiling water, and add the trimmed green beans. Blanch the beans for about 1 ½ minutes.
3. Drain the beans and transfer them to the bowl of ice water. When the beans are completely cooled, drain them and put them to the side.
4. Heat the olive oil in a large skillet to medium high heat. Add the mushrooms to the hot skillet to brown. Cook for 5 minutes.
5. Add the shallots, garlic, thyme and a pinch of salt and pepper. Cook for 3 minutes.
6. Add the butter and the flour. Turn the heat down to medium. Cook and stir for about 3 minutes.
7. Add the stock, and stir in the sour cream.
8. Once the sour cream is incorporated add the half-and-half, Worcestershire sauce, dry mustard, grated nutmeg and an additional dash of salt and pepper. Stir until combined.
9. Remove the skillet from the heat, add the blanched green beans and the lemon juice, toss to combine.
10. Transfer the beans and sauce to an 8 x 8 x 2 inch baking dish (or your favorite casserole).
11. Sprinkle the cheese evenly over the top of the beans.
12. Bake for 15 to 20 minutes, until the casserole is hot and bubbly.

*If desired, top with crispy fried onions or shallots.