Portabella Mushroom and Vidalia Onion Gratin

Course Side Dish

Cuisine American, Southern

Keyword mushroom-onion-gratin, portabella-mushrooms, vidalia-onion-recipes

Prep Time 20

Cook Time 30

Resting Time 5

Total Time 50

Servings servings

Calories 305kcal

Author Melissa Sperka

Ingredients

1 pound baby portabella mushrooms sliced
1 extra large vidalia onion or 2 medium sliced into small wedges
olive oil
1 tsp salt
1/2 tsp freshly ground black pepper
4 Tbsp butter divided
3 cloves garlic minced
2 tsp fresh thyme
1 Tbsp red wine vinegar
3 finely chopped green onions
2 1/2 Tbsp all purpose flour
1 1/2 cups whole milk
2 cups shredded Muenster cheese divided
2 Tbsp chopped Italian parsley divided
1 1/2 cups fresh bread crumbs
2 Tbsp grated Parmesan cheese

Instructions

Preheat the oven to 350°F. Butter the bottom and sides of a 1 1/2 quart baking dish, then set aside. (Alternately use single serving gratin dishes or an oven safe skillet.)
In a heavy saucepan, saute mushrooms and sliced onions in a couple of drizzles of olive olive. Cook for 10 minutes or until mushrooms are golden. Season with salt and black pepper, adjust to taste.
To the mushrooms, add 3 Tbsp butter, minced garlic, thyme, red wine vinegar and green onions.
Continue to saute over medium heat for 2 minutes just until the garlic has cooked and the butter has melted.
Add flour and stir until the flour has coated all of the ingredients.
Increase the heat to medium high and add 1 1/2 cups of milk. Cook until the mixture is bubbly and has begun to thicken. Around 2-3 minutes.
Add 1 1/2 cups of shredded cheese and 1 tablespoon of chopped Italian parsley to the pot. Mix just until the cheese melts. Remove from the heat mixing in 1 Tbsp parsley.
In a small bowl melt remaining 1 Tbsp butter in the microwave. Toss the breadcrumbs, Parmesan and remaining Italian parsley together.
Pour the mushrooms into the buttered baking dish and sprinkle the remaining shredded Muenster cheese and breadcrumbs on top.
Bake for 25-30 minutes until the topping is golden and the edges are bubbly.
Allow the gratin to sit on the counter for 5-10 minutes before serving to allow the sauce to thicken.

Notes

For this dish I purposely chose Muenster cheese for its saltiness. Gruyere cheese also works beautifully. Feel free to adapt using your favorite cheese in this dish.

Nutrition