Author: story of a kitchen (via smitten kitchen who adapted from martha stewart)
Recipe type: vegetable
Ingredients
4 tablespoons salted or unsalted butter, melted
4 tablespoons extra-virgin olive oil (I used my basil oil)
Coarse salt
4-5 pounds russet potatoes, peeled (smaller diameter potatoes are great, if you can find them)*
2 small onions
2 teaspoons dried thyme
Garnishes recommended by Deb (optional): Bits of goat cheese, crumbles of bacon and/or bits of crisped pancetta
Instructions
Preheat oven to 375 degrees F. In a small bowl, combine butter and oil. With a sharp knife or mandoline, slice potatoes crosswise very thinly (go thinner than 1.8 mm but no need to be transparently thin). Find an appropriate dish (see note below).*
Pour a tablespoon or so of the butter/oil mixture in the bottom and spread it evenly. Sprinkle the oil mixture with a few pinches of coarse salt. Be generous! This will allow you to season both the top and underside of the potatoes. Arrange potato slices vertically in the dish.
Thinly slice onions with mandoline and slide onion slivers between potato wedges, distributing them as evenly as possible. Brush with remaining oil/butter mixture. Generously season your dish with salt. Bake 1¼ hours, then sprinkle thyme on top and bake until potatoes are cooked through with a crisped top, about 35 minutes more. If casserole seems to brown quickly, cover with foil to avoid overbrowning. Add any garnishes, if using, and serve immediately. Serves 8.
Notes
* The amount you use will depend on the size of your baking dish. Martha suggests a 9-inch round dish. Since I used my oval-shaped 5-quart dish, I aimed higher. I used 4 pounds plus 10 ounces of peeled pre-sliced potatoes. There were some dark spots that I cut off before slicing, so the true amount was slightly less.
Recipe by story of a kitchen at https://www.storyofakitchen.com/vegetable-recipes/crispy-potato-roast/