Ingredients
- 1 lb fresh button mushrooms, sliced
- 2 tbsp. unsalted butter
- 12 slices white bread, crust trimmed and crumbled
- 1/2 c chopped sweet onion
- 1/2 c chopped celery
- 1/2 c chopped green bell pepper
- 1/2 c mayonnaise
- 1 tsp. kosher salt
- 1/2 tsp. freshly ground black pepper
- 2 large eggs
- 1 1/2 c whole milk
- 1 (10 ½-ounce) can cream of mushroom soup
- 1 c grated Swiss cheese
Instructions
- Prepare a large casserole dish with cooking spray.
- In a large skillet, sauté the sliced mushrooms in the butter over medium heat. Remove from the heat and place the mushrooms in a large mixing bowl.
- Place half of the bread crumbs in the bottom of the prepared casserole dish.
- To the mixing bowl, add the onion, celery, green bell pepper, mayonnaise, salt and pepper. Mix well to combine and pour the mushroom mixture over the bread crumbs in the casserole dish.
- In a small mixing bowl, stir together the eggs and milk. Pour egg mixture over the top of the casserole and cover. Top the casserole with the remaining bread crumbs. Let stand in the refrigerator overnight.
- Preheat the oven to 325°F.
- Remove the casserole from the refrigerator and uncover. Pour the cream of mushroom soup over the top of the casserole.
- Bake for 50 minutes. With 10 minutes remaining, sprinkle the grated cheese over the top.
- Remove from the oven and serve warm.