Blue Cheese Mushroom And Onion Potato Gratin

• 2 tablespoons oil
• 2 tablespoons butter
• 3 onions, halved then sliced
• 1 lb white button mushrooms, sliced (can use more mushrooms)
• 3 lbs russet potatoes (peeled and sliced very thin, about 1/8-inch thick)
• 3 cups whipping cream
• 3/4 cup blue cheese, crumbled (can use less blue cheese)
• 1 1/2 cups mozzarella cheese, grated
• salt and pepper

1. Heat oil and butter in a skillet; saute the onions until caramalized (about 10-12 minutes) remove with a slotted spoon to a bowl.
2. Add in the sliced mushrooms and saute until they loose there moisture (about 10 minutes) transfer to a bowl.
3. Set oven to 375 degrees (oven rack to second-lowest position).
4. Butter a 3-4 quart casserole dish.
5. In a 2-quart saucepan combine the potatoes with the whipping cream (the potatoes on top do not have to be covered completely) bring to a boil; remove from heat and cool to warm (about 30 minutes) leaving the potatoes in the cream.
6. Transfer one-third of the potatoes using a slotted spoon to the baking dish, spreading them out in an even layer.
7. Sprinkle with HALF of the onions, then HALF of the mushrooms; season with salt and pepper.
8. The sprinkle ONE-THIRD of both cheeses over the mushrooms.
9. Make another layer of potatoes then the sprinkle the REMAINING onions and mushrooms over the potatoes then another third of both cheeses.
10. Make one more layer with the remaining potatoes.
11. Top with remaining cheeses.
12. Pour any leftover whipping cream evenly over the top and cover tightly with foil.
13. Make for 45 minutes.
14. Increase the oven temperature to 400 degrees.
15. Remove the foil and bake until the top is golden brown, and the potatoes are fork-tender (about 12-15 minutes).
16. Let stand for 15 minutes before serving (the mixture will thicken upon standing).

oil, butter, onions, white button mushrooms, potatoes, whipping cream, blue cheese, mozzarella cheese, salt

Taken from www.food.com/recipe/blue-cheese-mushroom-and-onion-potato-gratin-148983 (may not work)