Creamy Mushroom Sauce Freezer Meal Prep
A silky mushroom cream sauce makes almost anything taste like a restaurant dinner, and this one is made weeks before you need it.
Onions and mushrooms soften in butter with sliced garlic and a sprig of rosemary. A little flour, a pour of broth and a splash of heavy cream turn it into a rich, spoonable sauce full of tender mushroom slices.
Freeze it in blocks, and on a busy night you just melt one in a skillet and spoon it over pasta, chicken, steak or mashed potatoes.
| Prep time | 10 minutes |
| Cook time | 25 minutes |
| Freeze time | 4 to 6 hours (hands-off) |
| Reheat time | 10 to 12 minutes, straight from frozen |
| Serves | 4 |
| Keeps | Up to 3 months in the freezer |
Why a Spoonful of Flour Is Worth It Here
The flour cooks into the butter and mushrooms before any liquid goes in, so it thickens the sauce without leaving a raw, pasty taste.
It also gives the cream something to hold on to. Cream sauces without a little starch can split or turn watery after freezing, while this one melts back into a smooth sauce.
Rosemary does the rest. One sprig simmered in the broth gives the whole batch a gentle, woodsy flavor that goes well with the earthy mushrooms.
Why Freeze the Sauce on Its Own
Keeping the sauce separate means you can decide what to serve it with on the night. Pasta, rice and potatoes all taste better cooked fresh, and they only take a few minutes while the sauce melts.
A big frozen block also takes up very little room in the freezer, and you reheat only what you need.
Ingredients
- 3 tablespoons unsalted butter
- 1 medium yellow onion, finely diced
- 1 pound white button mushrooms, sliced
- 4 garlic cloves, thinly sliced
- 2 tablespoons all-purpose flour
- 1 sprig fresh rosemary
- 1 cup chicken or vegetable broth
- 1 cup heavy cream
- Kosher salt, to taste
- Freshly ground black pepper, to taste
You will also need a large skillet with a lid, a silicone freezer mold, and a zip-top freezer bag to store the blocks once they are frozen.
How to Make Creamy Mushroom Sauce
Part 1: Make The Sauce
1. Slice The Mushrooms
Wipe the mushrooms clean with a damp paper towel and slice them about 1/4 inch thick. Even slices cook at the same rate, so none of them turn rubbery while others are still raw.
2. Melt The Butter
Set a large skillet over medium heat and add the butter. Let it melt completely and start to foam before anything else goes in.
3. Add The Onion
Tip in the diced onion and stir it through the butter. A fine dice melts into the sauce, so you get the sweetness without big chunks.
4. Season With Salt
Sprinkle a good pinch of kosher salt over the onion. Salting now draws out moisture and helps the onion soften faster.
5. Soften The Onion
Cook for 4 to 5 minutes, stirring often, until the onion is soft and translucent. Keep the heat moderate so it stays pale rather than browning.
6. Add The Mushrooms
Add all the sliced mushrooms at once. The pan will look very full, but they shrink by about half as they cook.
Cook for 6 to 8 minutes, stirring now and then, until they release their liquid and turn lightly golden.
7. Add The Garlic
Scatter in the sliced garlic and stir for about a minute, until it smells fragrant. Keep the garlic pale, because browned garlic turns bitter.
8. Sprinkle In The Flour
Sprinkle the flour evenly over the mushrooms and stir for a minute so it coats everything. Cooking it briefly in the butter gets rid of the raw flour taste.
9. Add The Rosemary
Lay the rosemary sprig on top of the mushrooms. It infuses the sauce as it simmers, and you can fish out the woody stem later.
10. Pour In The Broth
Pour in the broth and stir, scraping up anything stuck to the bottom of the pan. The flour will start thickening the liquid almost right away.
11. Simmer Until Slightly Thickened
Bring the sauce to a gentle simmer and cook for 3 to 4 minutes. You can partly cover the pan with the lid to keep it from reducing too fast.
12. Pour In The Cream
Lower the heat and pour in the heavy cream. It turns the broth pale and silky as soon as it goes in.
13. Stir And Season
Stir the cream through and let it bubble gently for 2 to 3 minutes, until the sauce coats the back of a spoon. Taste it and add more salt and some black pepper if it needs it.
Pull out the rosemary stem before freezing. A few loose needles left in the sauce are fine.
Part 2: Freeze
14. Cool And Portion Into Molds
Let the sauce cool to room temperature, then pour it into a silicone freezer mold and freeze until solid. Cooling it first stops ice crystals from forming, which keeps the cream from turning grainy later.
Once frozen, pop the blocks out and store them in a labeled zip-top freezer bag. Your mold is then free for the next batch.
These are the 1-cup silicone freezer molds I use to portion every component. Get the freezer molds on Amazon.
How to Reheat and Finish
15. Add The Frozen Block To A Skillet
Put a frozen sauce block straight into a skillet over medium-low heat. There is no need to thaw it first.
16. Cover And Heat Gently
Cover the skillet with a lid so the steam melts the block from all sides. Keep the heat gentle, because boiling cream sauce hard can make it separate.
17. Stir Until Smooth
Once the block has mostly melted, after about 10 minutes, remove the lid and stir until the sauce is smooth and hot all the way through. Add a splash of broth or water if it looks too thick.
18. Serve It Your Way
Spoon the sauce over freshly cooked pasta, seared chicken, pork chops, steak or a pile of mashed potatoes. Finish with a few grinds of black pepper.
Storage and Variations
The sauce blocks keep for up to three months in the freezer, so write the date on the bag.
Once the sauce has been reheated, eat it rather than refreezing it, and keep any leftovers in the fridge for up to three days.
For a deeper flavor, use a mix of cremini and white mushrooms, or swap the rosemary for a few sprigs of fresh thyme.
A handful of grated Parmesan stirred in at the end, or a squeeze of lemon juice, are both easy upgrades.
