To make stuffed mushrooms for a crowd, buy medium cremini mushrooms, about three per guest, pull out the stems and chop them fine, and cook them with sausage, shallot and garlic. Bind the filling with cream cheese, Parmesan and breadcrumbs, pack it into the caps, and bake at 400°F for about 20 minutes, until the tops are browned and the mushrooms are tender. Everything up to the oven can be done the day before.
Stuffed mushrooms are one of the few hot appetizers that hold up on a buffet. They are a single bite, they need no sauce, and a tray of forty bakes on two sheet pans in the same time as a tray of ten. The work is in the prep, and nearly all of it happens on the board.
What to buy
For 12 to 15 guests:
- 2 1/2 to 3 pounds medium cremini mushrooms, caps about the size of a walnut, roughly 40 caps
- 12 ounces bulk Italian sausage, mild or hot (or sausage links with the casings slit and removed)
- 2 shallots and 3 cloves garlic
- 4 ounces cream cheese, softened
- 1/2 cup finely grated Parmesan, plus more for the tops
- 1/2 cup panko breadcrumbs
- A small bunch of flat-leaf parsley
- Olive oil, salt and black pepper
Pick mushrooms of one size. A tray of matching caps bakes evenly; a mix of large and small leaves the big ones underdone while the small ones shrivel. White button mushrooms of the same size work with the same method.
For a vegetarian tray, leave out the sausage and double the chopped stems, adding a handful of finely chopped walnuts and a little more cheese.
Clean and stem the caps
Wipe each mushroom with a damp paper towel or a soft brush. If they are very dirty, rinse them briefly in a colander and spread them out on a towel to dry; do not leave them in a bowl of water. Wet caps steam rather than brown.
Hold a cap in one hand and press the stem sideways with your thumb. It snaps off cleanly at the base. Use the tip of a teaspoon to scrape out any stub that stays behind, along with a little of the gills if the hollow is shallow. A deeper hollow holds more filling.
Set the caps hollow side up on a sheet pan as you go. Keep the stems in a pile on the board.
Chop the stems fine
The stems are half the filling, so they need to be chopped very small, close to the texture of coarse sand. Trim off any woody or dirty ends first.
Gather the stems into a tight pile, set the knife over them, and rock the blade through the pile with your other hand flat on the spine near the tip. Scrape the pile back together with the side of the knife and rock through it again, five or six times, until no piece is larger than a grain of rice. This is the same fine dice used for duxelles, covered with the other cuts in how to cut mushrooms three ways.
Mince the shallots and garlic next, on the same board. How to mince a shallot shows the horizontal-and-vertical cuts that give an even mince without crushing it. Strip the parsley leaves and chop them last.
Cook the filling
The raw sausage never has to touch the board. Squeeze it straight from its package or casing into a wide skillet over medium-high heat, breaking it into small crumbles with a wooden spoon as it browns. The CDC lists 160°F as the safe internal temperature for ground meats such as pork. Cook it until no pink remains, and check a thick clump with an instant-read thermometer.
Wash your hands after handling the raw sausage, as the CDC advises after touching uncooked meat.
Push the cooked sausage to one side of the pan and add a tablespoon of olive oil, the chopped stems, the shallots and a pinch of salt. Cook, stirring, until the mushrooms have released their liquid and it has evaporated, about 8 minutes. Add the garlic for the last minute.
Scrape the mixture into a bowl and let it cool for 10 minutes. Stir in the cream cheese, Parmesan, half the panko and most of the parsley. Season with pepper and taste for salt; the sausage and cheese are both salty.
Fill and bake
Brush the outside of each cap with a little olive oil so it browns instead of drying out. Use two teaspoons, or a small cookie scoop, to mound the filling into each cap, pressing it in so it stays put. Mix the rest of the panko with a little more Parmesan and a drizzle of oil, and press a pinch onto each top.
Bake at 400°F for 18 to 22 minutes, until the tops are golden and a knife slides into the side of a cap with no resistance. Both pans can go in together on two racks; swap them halfway.
Making them ahead
Fill the caps up to a day ahead, cover the pans tightly and refrigerate them. Add the crumb topping right before baking, and give them 3 to 5 extra minutes, since they go into the oven cold.
Bake them in two rounds rather than all at once. Put out the first tray as guests arrive and the second an hour later. A fresh tray looks and tastes better than one kept warm all evening, and the CDC’s guidance is not to leave perishable food out for more than 2 hours. How to set up a holiday buffet explains the swap-a-fresh-platter approach in full.
Serving on the board
Let the mushrooms rest on the pan for 5 minutes, then move them to the serving board in neat rows with a spatula. Scatter the last of the parsley over them. Set out a small cup of toothpicks and a stack of cocktail napkins; a hot mushroom eaten off a toothpick is easier to manage than one picked up by the cap.
A wooden board makes a good warm-appetizer platter: the mushrooms do not slide, and the board keeps them looking like they came from a kitchen rather than a caterer. The WONAMU. bamboo cutting board is 12 by 9 inches, room for about twenty caps in rows, and its perimeter juice groove catches the oil and juices that run from the caps as they cool. Since the same board did the chopping, wash it in hot, soapy water and towel it dry before it goes out to the table.
Leftovers: refrigerate them within 2 hours in a covered container. Reheat them in a 350°F oven until hot through; the CDC’s figure for reheated leftovers is 165°F. The microwave turns the caps rubbery.
The short version
Buy about three medium cremini per guest, all one size. Snap out the stems, chop them fine on the board with the shallots and garlic, and cook them with crumbled sausage until the pan is dry. Bind with cream cheese, Parmesan and panko, fill the caps, and bake at 400°F for about 20 minutes.
Fill them a day ahead, bake in two rounds, and put out a fresh tray rather than keeping one warm.
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WONAMU. makes a bamboo cutting board designed for daily prep, 12 × 9 inches, bamboo, with a perimeter juice groove. Available on Amazon.
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