Step 1

Preheat Oven to 375˚F. Set a large pot with water over high heat and bring to a boil then add trimmed green beans. Cook/blanch them for 5 minutes for firmer beans or 8 minutes for softer beans. Drain and set aside.

Step 2

Meanwhile, Place a large pan over medium/high heat and add 1 Tbsp butter and 1 Tbsp oil, then add sliced mushrooms with a pinch of salt and pepper. Saute until the mushroom liquid has evaporated and mushrooms are golden.

Step 3

Move mushrooms to one side of the pan and add chopped onion. Saute onions over low heat for a couple of minutes then stir them together with mushrooms and saute until onions are soft (6-8 min). Add minced garlic and cook for 30 seconds longer while stirring.

Step 4

Add 2 Tbsp flour and stir until the flour turns into a paste. Continue cooking 1-2 minutes, stirring constantly until it smells slightly nutty, being careful not to burn the mixture.

Step 5

Add the 1/2 cup chicken stock and bring to a boil over medium heat, stirring constantly and scraping the bottom of the pan with a spatula. Add 1 cup heavy cream, 1 Tbsp Worcestershire sauce, 1 Tbsp soy sauce and cook over low until sauce has a creamy and gravy-like consistency (it thickens more as it bakes). Season with salt to taste.

Step 6

Add blanched green beans to the mushroom sauce and stir to combine then transfer to a casserole dish.

Step 7

In a separate bowl, combine 1/2 cup breadcrumbs, 1/3 cup parmesan cheese, 1/4 tsp garlic powder and 1 tsp dried parsley. Sprinkle over the green bean casserole. Bake uncovered at 375 F for 20 minutes then broil for 2-3 minutes until topping is golden.