Elevate your side dish game with this indulgent Blue Cheese Mushroom and Onion Potato Gratin. Layers of tender Yukon Gold potatoes are interwoven with sweet caramelized onions, earthy sautéed cremini mushrooms, and a luxurious blue cheese and Parmesan cream sauce, creating a rich and flavorful masterpiece. Fresh thyme adds a fragrant touch, while the bubbling golden crust ensures an irresistible finish. Perfect for holidays, dinner parties, or cozy family meals, this gratin is a creamy, savory delight that pairs beautifully with roasted meats or a crisp green salad. Ready in just over an hour, it’s an impressive yet approachable comfort food you’ll turn to again and again.
Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with olive oil or butter.
Peel the Yukon Gold potatoes and use a mandoline slicer or sharp knife to slice them into 1/8-inch thick rounds. Set aside in a bowl of cold water to prevent browning.
Slice the onion into thin half-moons and roughly chop the cremini mushrooms. Mince the garlic cloves.
Heat a large skillet over medium heat and melt 2 tablespoons of butter. Add the onions, a pinch of salt, and cook, stirring occasionally, for 10 minutes until caramelized. Remove from the skillet and set aside.
In the same skillet, melt the remaining 1 tablespoon of butter. Add the mushrooms and garlic, and sauté for 5-6 minutes until the mushrooms release their moisture and are golden brown. Stir in 1 teaspoon of thyme and set aside.
In a small saucepan, heat the heavy cream over low heat until warm. Stir in the blue cheese, Parmesan cheese, salt, pepper, and 1 teaspoon of thyme until smooth. Remove from heat.
Drain the potato slices and pat them dry. Layer one-third of the potatoes in the prepared baking dish, slightly overlapping. Spread half of the caramelized onions and half of the sautéed mushrooms over the potatoes. Repeat these layers and finish with a final layer of potatoes.
Pour the cheese and cream mixture evenly over the potatoes, ensuring it reaches all layers. Cover the baking dish tightly with aluminum foil.
Bake in the preheated oven for 40 minutes. Remove the foil and bake for an additional 20 minutes, or until the top is golden brown and the potatoes are tender when pierced with a knife.
Garnish with a sprinkle of fresh thyme before serving. Let the gratin cool for 5-10 minutes before slicing and serving.
Calories |
3274 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 216.1 g | 277% | |
| Saturated Fat | 130.7 g | 653% | |
| Polyunsaturated Fat | 0.0 g | ||
| Cholesterol | 618 mg | 206% | |
| Sodium | 5578 mg | 243% | |
| Total Carbohydrate | 240.6 g | 87% | |
| Dietary Fiber | 21.8 g | 78% | |
| Total Sugars | 23.3 g | ||
| Protein | 90.3 g | 181% | |
| Vitamin D | 0.8 mcg | 4% | |
| Calcium | 1773 mg | 136% | |
| Iron | 10.9 mg | 61% | |
| Potassium | 6626 mg | 141% | |
*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.