Now, this is a substantial side dish! Actually, it’s a side dish that could be considered an entrée, with one or two other vegetables and a grain dish on the plate. I came up with this recipe when I saw that I had some chive cream cheese in the fridge that I wanted to use before it became over-the-hill. I decided to make a quick “creamed spinach” by stirring some of the chive cream cheese into hot, freshly cooked spinach. Then I piled the creamed spinach on top of cooked Portobello mushroom caps and then topped the whole thing off with grated cheese. After baking, the stuffed mushrooms were truly delicious and incredibly substantial.
If you don’t feel like making your own chive or scallion cream cheese, just pick some up at the neighborhood bagel shop. That will work perfectly in this recipe.
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After cleaning and drying the spinach leaves, heat 4 tablespoons of the olive or Garlic Confit oil in a 6-to 8-quart, heavy-bottomed saucepan over high heat. When the oil is hot, add the spinach leaves, by the handful, using tongs to help wilt the leaves, creating the room for more spinach to be added. When all the leaves are in the pan, toss them in the oil and apply the lid. Reduce the heat to low and cook the leaves until just tender, stirring occasionally, 3 to 4 minutes. Place a medium-mesh sieve over another bowl and pour the cooked spinach into the sieve, allowing any liquid to fall through the sieve and into the bowl. Place a bowl on top of the spinach, helping to release more of the liquid. (You can reserve the flavorful spinach liquid and use it to cook rice.) Put the hot spinach in an empty bowl and stir in the scallion (or chive) cream cheese. When homogenous, season the filling with salt and pepper to taste.
After removing the stems and cleaning the mushroom caps, brush them, on both sides, with a mixture of the remaining extra-virgin olive oil, minced garlic, black pepper and thyme, if using. Heat a grill pan or a large nonstick skillet over high heat (turn on your exhaust fan). Alternatively, preheat the broiler with the rack as close as possible to the heating element. Sprinkle the mushroom caps lightly, but evenly, with salt. Grill, sear or broil the seasoned caps, turning once, until deeply colored and tender, about 4 to 6 minutes, total (brush with more olive oil, while cooking, if they seem at all dry). Place the cooked mushroom caps, gill sides up, on a baking sheet, lined with aluminum foil (shiny side up).
Preheat the oven to 375°F with the rack in the second closest position to the heating element. Spread the spinach stuffing equally among all the mushrooms, mounding slightly, then sprinkle the mixed cheese over the filling. Give one more application of pepper. Bake the mushrooms, uncovered, until the filling is piping hot and the cheese is melted, 20 to 30 minutes. If the cheese isn’t as luscious looking as you’d like, broil the tops for a minute or two. Serve hot.
If making the scallion cream cheese, it can be made several days ahead (up to 3) and kept refrigerated, securely covered.
The spinach can be cleaned two days ahead and kept refrigerated in a large freezer bag. (Line the bag with some paper towels to absorb any excess moisture.)
The mushrooms can be seasoned a day ahead of cooking and kept refrigerated.
The mushrooms can be stuffed a day ahead and kept refrigerated, well covered. Bring close to room temperature before baking or adjust (lengthen) the baking time, accordingly.