All-in-one Steakhouse Sides
(Hash browns topped with creamed spinach, mushrooms, and cheese)
2 large russet potatoes, scrubbed
8 to 9 ounces baby spinach
6 white or crimini mushrooms, sliced
1 large shallot, minced
1 tablespoon flour
¾ cup milk
1/3 cup grated Gruyère cheese
Salt and freshly-ground pepper
Put the potatoes in a saucepan and cover with water by at least an inch. Put the pot over high heat, bring to a boil, then simmer the potatoes until tender, about a half hour. Drain the potatoes and put them on a plate in the fridge for at least 2 hours, until cold. You can also do this a day ahead.
Peel the cold potatoes, then grate them on the large holes of a box grater. You should have between 2-1/2 and 3 cups. Heat 2 tablespoons of butter and 1 tablespoon of olive oil in an 8-inch nonstick skillet. When the foam subsides, add the potatoes, a big pinch of salt, and some pepper. Stir with a heatproof spatula to get everything well-coated, then press the potatoes into a flat layer in the pan. Let it cook over medium-low heat for 20 minutes or so, shaking the pan occasionally. It should be nicely golden on the bottom.
In the meantime, heat a tablespoon of olive oil in a large skillet, and saute the shallot with a pinch of salt until just starting to brown. Add the spinach a handful at a time, and cook until the spinach is wilted. Scrape the mixture into a small-holed strainer/colander and let it drain and cool for a few minutes. Wipe out the pan, add a tablespoon of butter, and heat until the foam subsides. Add the mushrooms and a little salt, then cover the pan and cook for about 5 minutes so the mushrooms release their liquid. Uncover the pan, raise the heat, and cook until they start to brown, about 3 minutes more. Set the mushrooms aside in a small bowl.
At this point, you’re ready to flip the potatoes. Have a dinner plate at the ready. Turn off the heat and move the skillet to a cool spot. Put the plate upside down on top of the skillet. Using potholders or kitchen towels, grab the whole thing –plate, skillet, and all – and turn it over. Take the skillet off. The potatoes will be cooked-side down. Brush the top, uncooked side with a little olive oil. Then put the skillet upside down over the potatoes and flip the whole thing again so the potatoes are back in the pan. Press the potatoes down with the spatula, and let cook over medium-low heat for another 15-20 minutes, until browned on the bottom.
When the spinach is cool enough to handle, put the whole bundle in a large, clean kitchen towel (I have a green one just for this purpose). Wrap up the sides of the towel, then squeeze over the sink to remove as much liquid as possible. Set it aside.
Melt a tablespoon of butter in a medium saucepan, then add the flour. Stir well, and cook for about a minute. Add the milk, and stir or whisk until it’s smooth. Bring to a boil over medium-low heat, stirring constantly. The mixture should thicken a little. Turn off the heat, add the Gruyère and mix well. Stir in the spinach and mushrooms.
Slide the potato cake onto a serving platter and top with the spinach/mushroom/cheese sauce. Cut into wedges and serve right away.