Bring a large pot of salted water to a boil. Meanwhile, fill a large bowl with ice water and set nearby.

Add the trimmed and halved green beans to the boiling water and blanch for 4–5 minutes, until bright green and just barely tender but still with a good bite.

Drain the beans immediately and plunge them into the ice water bath. Let sit for 2 minutes, then drain well and pat dry with paper towels. Set aside.

Preheat your oven to 375°F (190°C). Lightly spray a 9x13 inch baking dish with cooking spray.

In a large oven-safe skillet or wide saucepan, melt the butter with olive oil over medium-high heat. Add the sliced cremini mushrooms in a single layer and cook undisturbed for 3–4 minutes until golden on the bottom. Stir and continue cooking another 2–3 minutes until the mushrooms are deeply browned and any liquid has evaporated.

Add the minced garlic and fresh thyme to the mushrooms and cook, stirring, for 60 seconds until fragrant.

Sprinkle the flour over the mushroom mixture and stir well to coat. Cook for 90 seconds, stirring constantly, to eliminate the raw flour taste.

Slowly whisk in the skim milk, a little at a time, followed by the broth and soy sauce. Whisk continuously to prevent lumps. Bring to a gentle simmer over medium heat, stirring frequently, until the sauce thickens enough to coat the back of a spoon — about 4–5 minutes.

Season with salt, pepper, garlic powder, and a pinch of nutmeg. Taste and adjust seasoning as needed. Remove from heat.

Add the blanched and dried green beans to the mushroom sauce and fold gently until evenly coated.

Transfer the green bean and sauce mixture to the prepared 9x13 inch baking dish and spread into an even layer.

In a small bowl, toss together the panko breadcrumbs, sliced almonds, olive oil, salt, and garlic powder until the panko is lightly coated.

Sprinkle the topping evenly over the green bean mixture.

Cover the dish loosely with foil and bake for 20 minutes. Remove the foil and bake for an additional 12–15 minutes, until the topping is deep golden brown and the sauce is bubbling at the edges.

Remove from the oven and let rest for 5 minutes. Garnish with fresh chopped parsley if desired and serve hot.

Assemble the casserole through Step 3 (do NOT add the topping). Cover tightly and refrigerate for up to 24 hours. When ready to bake, add the panko-almond topping cold straight from the fridge, cover with foil, and bake at 375°F for 25 minutes covered, then 12–15 minutes uncovered until golden and bubbling.