4large sweet potatoes(about 2 ½ pounds; peeled and very thinly sliced)
1cupshredded cheese(such as Gruyere or sharp cheddar; optional)
Instructions
Preheat the oven to 375 F. Spray a 2-quart shallow baking dish or a 9-inch square pan with nonstick cooking spray.
Heat the butter in a large deep skillet over medium heat. When the butter is melted, add the onions and shallots and sauté for about 5 minutes until the vegetables are tender. Don’t let the vegetables brown – turn down the heat if necessary, and stir frequently. Stir in the oregano or thyme, salt, pepper, and red pepper flakes if using. Add the cream and half-and-half and bring to a simmer, stirring occasionally.
Place half of the potatoes in the prepared pan. Carefully pour half of the hot liquid over the potatoes, using a spoon to scoop out some of the onions and shallots as your pour. Fill the pan with the rest of the potatoes and pour over the rest of the liquid. Sprinkle over the cheese, if using.
Cover with foil and bake for 30 minutes, then remove the foil. Press lightly on the top with a spoon to re-submerge the potatoes, and bake for another 30 minutes until the top is golden brown and a knife inserted into the potatoes goes in with almost no resistance.
Serve hot.
Notes
I used 1 cup cream and 1 cup half-and-half to make these, but you could pick a lane and stick with one or the other.
When you pour in the sauce, make sure to scoop out some of the onions and shallots onto the potatoes so that they are evenly distributed in the casserole.
The cheese is optional — leave it out if there is cheese in anything you are serving these potatoes alongside.