Ryan Scott's Green Bean Casserole with Celery Root and Bacon

Preheat oven to 350°F.

Wash then blanch green beans. Cut beans in half and set aside. Cook bacon until crispy. Set on plate with paper towel to let oil drain. In the same pan, blister button mushrooms until golden brown. Dice bacon and slice button mushrooms in half. Reserve cooking oil.

Crush fried onions and bread crumbs into medium-sized bits and reserve.

For the béchamel, rinse the celery root and cut off dirty part. Chop the white interior into 1/2-inch cubes. Melt the butter in the same saucepan you used to cook the mushrooms and bacon over medium heat. When the butter is melted, add celery root and onions. Cook until vegetables start to become tender, about 10 minutes. Add flour and stir until mixture is thick. Continue to stir, slowly pouring in milk. Turn the heat up while constantly stirring until mixture begins to boil. Reduce heat to low and cook about 20 minutes; scrape bottom of pan occasionally to prevent burning. Remove from heat and allow to cool.

Once mixture is cool, add whole grain mustard and purée mixture with an immersion blender.

Pour the mixture into casserole dish and fold in bacon, blistered button mushrooms, blanched green beans and parsley. Place the mixture in oven for about 20 minutes until hot. Cover casserole with onion crumble and place back in oven 5 minutes or until golden brown. Remove and serve.