Preheat and prep: Heat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish. Pat the pork dry and season with 1 teaspoon salt, 1/2 teaspoon pepper, and the paprika.

Blanch the green beans: Bring a large pot of salted water to a boil. Add green beans and cook 3–4 minutes until bright green and slightly tender. Drain and rinse under cold water to stop cooking. Set aside.

Sear the pork: Heat 1 tablespoon olive oil in a large skillet over medium-high. Add half the pork in a single layer and sear 2–3 minutes per side until lightly browned but not fully cooked. Remove to a plate. Repeat with remaining oil and pork.

Sauté aromatics: Reduce heat to medium. Add butter to the skillet. Once melted, add onion and mushrooms with a pinch of salt. Cook 5–6 minutes until softened and lightly browned. Stir in garlic and thyme; cook 30 seconds until fragrant.

Make the sauce: Sprinkle flour over the vegetables. Stir and cook 1 minute. Slowly whisk in chicken broth, then milk, until smooth. Simmer 2–3 minutes until slightly thickened.

Finish the sauce: Stir in sour cream, Dijon, and Worcestershire. Taste and season with salt and pepper. If using cheese, stir in half now to melt.

Combine in the dish: Add blanched green beans and seared pork to the baking dish. Pour the sauce over and gently toss to coat. Sprinkle remaining cheese on top if using.

Add the topping: Mix your crunchy topping with a tablespoon of melted butter (optional) and sprinkle evenly over the casserole.

Bake: Bake 20–25 minutes until bubbling around the edges and the topping is golden. Pork should reach an internal temperature of 145°F (63°C).

Rest and serve: Let the casserole rest 5–10 minutes. Garnish with chopped parsley and serve warm.