Creamy Green Bean Casserole

1. Preheat the oven to 350°F and lightly grease a 9x9-inch baking dish.
2. Blanch the green beans: Bring a large pot of salted water to a boil. Add the washed, trimmed, green beans and cook for 3 minutes. Drain and immediately transfer to a bowl of ice water to stop the cooking process. Drain again and set aside.
3. Make the sauce: In a large skillet over medium-high heat, melt the butter. Add the diced shallots (or onion) and minced garlic. Sauté for 2 minutes, until fragrant.
4. Stir in the salt, black pepper, thyme, and cayenne pepper. Sprinkle in the flour and stir constantly for 1 minute to cook out the raw flour taste.
5. Reduce the heat to medium-low. Slowly pour in the heavy cream and milk, whisking until smooth and slightly thickened.
6. Add the Boursin cheese, breaking it apart with a spoon, and whisk until fully melted and smooth. Turn off the heat, then stir in the Parmesan cheese until creamy.
7. Assemble the casserole: Add the blanched green beans and 1 cup of crispy fried onions to the sauce. Stir to coat evenly.
8. Transfer the mixture to the prepared baking dish and top with the remaining crispy fried onions.
9. Bake uncovered for 30 minutes, or until hot, bubbly, and golden on top.
10. Serve warm and enjoy your rich, creamy green bean casserole!