2 lbs., Green beans, ends trimmed and cut into 1.5” pieces
2 Tbsp Avocado oil (or other neutral oil), divided
1 ¼ cup Yellow onion, diced
1 lb. Cremini mushrooms, sliced ¼” thick
3 Tbsp. Unsalted butter, divided
2 sprigs Fresh thyme + more for garnish
3 large Garlic cloves, minced
½ tsp. Mustard powder
3 Tbsp. All purpose flour
2 cups a2 Milk® Whole
1 – 1 ½ tsp. Sea salt
½ tsp. Coarse ground black pepper
Zest 1 Lemon
1 ½ cups Almond slivers or slices
Preheat oven to 375℉ and bring a stockpot of salted water to boil.
Cook green beans in boiling water for 3 minutes or until bright green. Remove from water, drain, and set aside in a bowl.
Heat 1 tablespoon oil in a large skillet over medium heat and sauté diced onion until translucent, then push to the side of the skillet. Turn heat up to medium-high and add half the mushrooms. Sauté without stirring for 2 minutes or until golden brown on one side. Toss and continue cooking for additional 3 minutes, season with salt and transfer to bowl with green beans. Add remaining tablespoon oil and cook remaining mushrooms undisturbed for 2 minutes, then add 1 tablespoon butter and two sprigs thyme and continue to cook another 3 minutes. Season with salt and transfer to reserved bowl.
In a large saucepan, heat remaining 2 tablespoons butter over medium low heat. Add garlic and cook 1 minute until fragrant. Whisk in flour to make a roux, cooking until golden and nutty (about 4 minutes). Slowly whisk in milk. Then add mustard powder, ½ tsp pepper, and ½ tsp salt.
Increase heat and stir constantly so the bottom doesn’t burn cooking until sauce begins to simmer and thickens enough to coat a spoon.
Arrange mushrooms and green beans in a 2 quart baking dish and pour cream sauce over them. Sprinkle the lemon zest and gently toss green beans with the sauce. Cover with foil and bake for 25 minutes until bubbling. Then remove from the oven.
Increase oven temperature to 400℉. Evenly sprinkle the almonds over the green beans. Continue cooking uncovered for 8 minutes or until the topping is golden brown being careful not to burn.
Let the casserole sit for 5 minutes before enjoying!