One More Way To Enjoy the South's Beloved Vidalia Onion
Portabella Mushrooms and Vidalia Onions Pair Beautifully In This Gratin
We love mushrooms alongside steaks or chicken either grilled or sauteed. When sauteed, I usually add minced garlic, chopped onion, a splash of balsamic vinegar, a sprig of fresh rosemary or whatever other seasonings that are ready to be used from my herb garden. This portabella mushroom and onion gratin is sprinkled with a crunchy breadcrumb topping making it an incredible way to change up your side dish menu. Filled with tasty cheesy mushrooms and Vidalia onions and a crispy crumb topping, it can be baked in one dish or you can divide it among several gratin dishes for a gorgeous presentation for individuals.
Other Ways To Enjoy Portabella Mushroom and Vidalia Onion Gratin
While this Portabella Mushroom And Vidalia Onion Gratin is primarily enjoyed on the side, it's also delightful served as a topping for baked potatoes, ladled over egg noodles or buttered rice. Try spooning this gratin over a piece of Italian seasoned grilled chicken topped with a sprinkle of cooked pancetta or bacon. It's heavenly! If you love Vidalia onions too, checkout my recipe featured by Parade Magazine for Vidalia Onion Pepper Relish here.
Grilled Steak and Portabella Mushroom And Vidalia Onion Gratin
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Helpful Kitchen Items:
Portabella Mushroom and Vidalia Onion Gratin
- 1 pound baby portabella mushrooms sliced
- 1 extra large vidalia onion or 2 medium sliced into small wedges
- olive oil
- 1 tsp salt
- ½ 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 ½ Tbsp all purpose flour
- 1 ½ cups whole milk
- 2 cups shredded Muenster cheese divided
- 2 Tbsp chopped Italian parsley divided
- 1 ½ cups fresh bread crumbs
- 2 Tbsp grated Parmesan cheese
- Preheat the oven to 350°F. Butter the bottom and sides of a 1 ½ quart baking dish, then set aside. (Alternately use single serving gratin dishes)
- 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 ½ cups of milk. Cook until the mixture is bubbly and has begun to thicken. Around 2-3 minutes.
- Add 1 ½ 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.