Creamy Polenta Mushrooms in 20 Minutes
Watch the Full Step-by-Step
- Baking sheet
- Small saucepan
- Pastry brush
INGREDIENTS
- 8 large portobello mushrooms, stems removed
- 3 tablespoons olive oil
- 2 cups/480 milliliters milk
- 1½ cups/360 milliliters water
- ½ cup/120 milliliters heavy cream
- 3 tablespoons unsalted butter
- ¾ cup/120 grams cornmeal
- 1 teaspoon salt
- 3 tablespoons grated Grana Padano, plus more for serving
INSTRUCTIONS
- Heat the oven to 350°F/180°C.
- In a small saucepan, bring the milk, water, cream and butter to a boil. Reduce the heat to medium and gradually whisk in the cornmeal. Cook, whisking constantly, until thickened, about 8 minutes. Stir in the Grana Padano.
- Remove the stems. Using a teaspoon, gently scoop out some of the flesh to create a shallow cavity in each mushroom.
- Brush the mushrooms with olive oil and arrange them on a parchment-lined baking sheet. Spoon the polenta into the mushroom caps, leaving a little room at the top.
- Bake until the mushrooms are tender and the polenta is hot, about 10 minutes. Serve warm, topped with additional Grana Padano.
FAQ
Can I use a different type of mushroom instead of portobello mushrooms?
Large cremini mushrooms, also called baby bella mushrooms, can replace portobellos, although their smaller size means they will hold less polenta. Choose mushrooms with broad, deep caps if you want a generous filling. Large flat mushrooms are also suitable because they provide enough surface area to form a cavity for the polenta. Avoid delicate mushrooms with very thin caps, since they can become overly soft during baking.
The cooking time may need to be adjusted depending on the size and thickness of the mushrooms. Smaller mushrooms will usually become tender more quickly, while thicker mushrooms may require a few additional minutes. For the best polenta mushrooms, choose mushrooms that are firm, dry, and free of significant bruising or sliminess. Clean them gently with a damp paper towel rather than soaking them in water, which can make them difficult to brown and bake properly.
How can I make the polenta mushrooms more filling for a main course?
The recipe can serve as a vegetarian main course when paired with substantial sides or additional ingredients. To make the mushrooms themselves more filling, you can incorporate cooked vegetables, beans or finely chopped mushrooms into the polenta. Sautéed spinach, roasted peppers, caramelized onions or finely chopped sautéed mushrooms can add both volume and flavor.
White beans or chickpeas can provide additional protein and make the meal more substantial, although they should be finely chopped or folded into the filling so it remains easy to spoon into the mushroom caps. Serving the polenta mushrooms with a green salad, roasted vegetables or a bean salad also creates a more complete meal. If using additional ingredients in the polenta, avoid making the filling excessively loose because it needs to remain thick enough to sit inside the mushroom caps during baking.
How do I keep the polenta creamy and prevent it from becoming too thick?
The most important factor is the cooking process. Gradually whisk the cornmeal into the hot milk, water, cream and butter instead of adding it all at once. This helps prevent lumps and allows the cornmeal to hydrate evenly. Once the cornmeal is incorporated, continue whisking as it cooks over medium heat until the polenta thickens, which takes about 8 minutes in this recipe.
Avoid cooking it over high heat because excessive evaporation can make it too thick before the cornmeal is fully cooked. Grana Padano is added at the end, after the polenta has thickened, which gives it a smooth, savory finish without requiring additional cooking. For these polenta mushrooms, the finished polenta should be thick enough to spoon into the mushroom caps but still soft and creamy. If it becomes too firm, stir in a little warm milk before filling the mushrooms.
Can I use whole-grain cornmeal instead of regular cornmeal?
Yes, although whole-grain cornmeal can produce a noticeably different texture and flavor. It generally contains more of the corn kernel and can have a coarser texture than finely ground cornmeal. Because of this, it may take longer to soften and may require additional liquid depending on the grind. For creamy polenta mushrooms, a medium or fine cornmeal is generally easier to use because it produces a smoother filling that can be spooned neatly into the mushroom caps.
If you substitute whole-grain cornmeal, check its cooking instructions and allow extra time if necessary. The finished polenta should be tender rather than gritty. Avoid using cornmeal that is extremely coarse unless you specifically want a more rustic texture. The cheese, butter and dairy in the recipe provide richness, but they cannot completely eliminate the texture of undercooked coarse cornmeal.
Can I make these polenta mushrooms without heavy cream?
The heavy cream can be replaced with additional milk, although the finished polenta will be slightly less rich and creamy. Because this recipe already contains butter and Grana Padano, the polenta will still have a smooth texture and savory flavor without the cream. You can also replace the heavy cream with an equal amount of half-and-half for a texture that falls between milk and heavy cream.
When using only milk, watch the polenta as it cooks because the lower fat content can make it seem slightly thinner and less luxurious. The cooking method remains the same: bring the liquid and butter to a boil, reduce the heat, gradually whisk in the cornmeal, and cook until thickened. The mushrooms themselves do not require any changes when you modify the dairy ingredients, so the finished polenta mushrooms can be prepared using the same baking time.
Can I add herbs, garlic, or other seasonings to the polenta?
The basic polenta provides a mild, creamy base that can accommodate additional seasonings without changing the structure of the recipe. Finely minced garlic can be cooked briefly in the butter before the milk, water and cream are added, although it should not be browned heavily because that can make it bitter. Fresh thyme, rosemary or parsley can also complement the mushrooms. Thyme is particularly well suited because its earthy flavor works naturally with portobello mushrooms.
Black pepper can be added along with the salt, while a small amount of crushed red pepper can provide heat. If you add strongly flavored ingredients, keep the seasoning moderate so the Grana Padano and mushrooms remain noticeable. For polenta mushrooms intended as a side dish, simple additions such as black pepper and fresh thyme are usually enough to add flavor without overwhelming the creamy polenta.
What can I use instead of Grana Padano in this polenta mushrooms recipe?
Parmesan cheese is the most straightforward substitute for Grana Padano because it has a similar firm texture, salty flavor and nutty character. Finely grated Parmigiano-Reggiano will also work and will give the polenta a slightly more pronounced savory flavor. Pecorino Romano can be used, but it is noticeably saltier and sharper, so you may want to reduce the amount of added salt in the polenta.
For a milder result, a finely grated aged provolone can provide richness without the stronger flavor of Pecorino. Whichever cheese you choose, grate it finely so it melts smoothly into the hot polenta. The cheese also works as a finishing ingredient, so reserve some for sprinkling over the baked mushrooms just before serving. A good melting cheese with a savory profile will preserve the character of these polenta mushrooms while allowing you to adapt the recipe to what is available.
How do I prevent the portobello mushrooms from becoming watery?
Portobello mushrooms naturally contain a significant amount of water, which is released as they cook. To minimize excess moisture, avoid soaking the mushrooms when cleaning them. Instead, wipe them gently with a damp paper towel or use a soft brush to remove visible dirt. Make sure the mushrooms are reasonably dry before brushing them with olive oil. Baking them on a parchment-lined sheet at 350°F/180°C allows them to release moisture while the polenta heats through.
Avoid overcrowding the baking sheet because closely packed mushrooms can trap steam and become softer. Choose firm mushrooms rather than caps that already feel wet or slimy. Because the mushrooms are baked for only about 10 minutes in this recipe, they retain some structure rather than cooking long enough to release a large amount of liquid. These steps help the polenta mushrooms maintain a better texture.
How should I store and reheat leftover polenta mushrooms?
Store leftover polenta mushrooms in an airtight container in the refrigerator for up to 3 days. Allow them to cool before covering and refrigerating them, but do not leave cooked food at room temperature for more than 2 hours. For the best texture, reheat the mushrooms in a 350°F/180°C oven until the filling is hot and the mushrooms are warmed through. An oven or toaster oven is preferable to a microwave because it reheats the mushrooms more evenly and helps prevent the polenta from becoming excessively soft.
If using a microwave, heat individual portions in short intervals until hot, keeping in mind that the mushrooms may release additional moisture. The polenta may firm up during refrigeration, which is normal. These polenta mushrooms are best eaten within 3 days and should be refrigerated promptly after serving rather than repeatedly cooled and reheated.
Can I use instant polenta or quick-cooking cornmeal for these polenta mushrooms?
Yes, but the cooking time and liquid requirements may differ from the cornmeal specified in the recipe. Instant polenta is precooked and hydrates much faster than traditional cornmeal, so it generally requires only a few minutes of cooking. Follow the package directions for the appropriate liquid ratio rather than automatically using the quantities in this recipe.
The goal is to produce a thick, spoonable polenta that holds its shape inside the mushroom caps. If the polenta is too loose, it may spill over during baking; if it is too firm, it can become dense after reheating. For these polenta mushrooms, quick-cooking polenta can be a practical shortcut when time is limited. Stir the Grana Padano into the finished polenta after it has reached the desired consistency, then fill and bake the mushrooms as directed.
