Creamy Mushroom Sauce

This wonderfully creamy and rich mushroom sauce is the best keto side dish to elevate your homemade steak dinner to restaurant quality!

Mushrooms are infused in garlic and butter and simmered with cream and mustard to create a flavorful and silky sauce that ‘s just sinful over steak, chicken, turkey and even vegetables!

Creamy keto mushroom  sauce spooned over pink sirloin steak.

This keto mushroom sauce recipe was created and cooked entirely by Daniel – I’m just the tech support here (photography and writing). I helped eating, too!

We love mushrooms but don’t eat them as often as we’d like. I think that’s because cooking with mushrooms takes some planning, as one can’t just have fresh mushrooms available in the fridge at all times.

Our approach to cooking starts with – Today I feel like… then – Let’s see if we have the ingredients and finally either – Bummer or – Yess!! – So that’s how this mushroom sauce happened 😁

Keto creamy mushroom sauce in a serving plate, with a spoon.

The ingredients

The LikeHotKeto mushroom steak sauce needs very few keto friendly ingredients that you probably already have!

If not, here’s also some ingredient substitution tips:

The ingredients for keto creamy mushroom sauce recipe.
  • Mushrooms: I used cremini for their firmer texture and meatier flesh, but any fresh mushrooms you like will do.
  • Butter: If you can, use grass-fed European butter – the intense flavor is totally worth it!
  • Heavy cream or whipping cream: Non-keto sauces usually take milk and thickener instead of cream, to make to them lighter. That’s definitely not the case here 😂
  • Mustard: You can use dry mustard, or crushed yellow mustard seeds, or smooth Dijon mustard.
  • Garlic and onion: Sautéed in butter, they sweeten and form a wonderful base of flavor.
  • Salt, black pepper and thyme: I give specific quantities as a guide for beginner cooks in the recipe card, but as always you can (and should!) adjust all spices to taste.
Keto dinner served on a plate, with steak, mushroom steak sauce and giant pickles.

Which mushrooms are best for sauce

Mushrooms that are a bit firmer and meatier hold up better being sautéed and simmered for some time without getting too soft or soggy with no texture.

So the cremini (also called crimini or baby bella) is a better choice, instead of the simple white button mushrooms, which are their softer younger version.

Portobellos are not the best match for sauces, as they are much firmer than needed and a bit too chewy.

How to clean mushrooms

You can wash the mushrooms in water, but it’s not a good idea to have them soak for any period of time.

That’s because mushrooms are like an absorbent sponge. This is a marvelous characteristic as they will take on flavors so easily, but you’ll want to keep them out of water for the same reason.

I usually put the mushrooms in a colander and swirl them around in running water to remove the dirt.

Another good way of washing mushrooms while keeping them from absorbing water is gently rubbing them with a wet cloth or paper towel.

Keto mushroom sauce over green beans.
Mushroom sauce is a classic on steak, but don’t let that deter you from serving over veggies

How to make

This keto mushroom sauce recipe is really simple and straight-forward, I bet you’ll be repeating this many times as we do!

1. Cut the mushrooms, or not

First, decide how you want the mushrooms in your sauce: We prefer it sliced, not too thinly so they get soft but still have a nice bite to them.

If using white mushrooms instead of the baby bellas, you might just quarter or half them, or even keep them whole if they are smaller. This is because they are softer and more delicate.

Step by step of making the keto mushroom steak sauce.

2. Sauté to create flavor

Start by heating up a large saucepan or skillet, adding some butter to melt and the chopped onions to sauté until they’re soft and translucent.

At this point, add the garlic. The garlic is not added together initially with the onion because it doesn’t need to be cooked as long. Just one minute or two is enough to make it golden and bring out the best flavor.

Now add more butter. When it’s melted and hot, it’s finally time to add the mushrooms! Also the salt, black pepper and mustard powder.

The mushrooms will shrink, letting go of water as they cook (the salt helps), while absorbing the flavors of the garlic, butter and spices.

3. Make it creamy

When the mushrooms are soft and buttery, add the heavy or whipping cream and thyme leaves. Gently simmer until the sauce thickens.

This keto mushroom sauce is not supposed to be super thick, but it can be if you let it simmer for a longer time. For a rich, creamy texture, about 5 minutes is enough.

Steak strips covered with creamy keto mushroom sauce with garlic and butter.

What to serve with keto mushroom sauce

Creamy mushroom sauce is classically served over thick and juicy steaks (I’m getting hungry just from imagining it!) but there are many other uses for it:

This easy mushroom sauce is also great with poultry, elevating plain and simple chicken breasts to “to die for” status!

Make it as a Thanksgiving dinner side dish with this easy one-pan oven roasted turkey breast and veggies! Talk about a complete low-carb and healthy holiday meal in record time!

And why not serve this mushroom and mustard sauce as topping for veggies? Use it to take plain grilled, steamed or air fried veggies to a higher level of deliciousness!

Creamy keto mushroom butter & garlic sauce topping thick slices of medium-rare pink steak, on a white plate.

Storage and making ahead

You can serve this keto mushroom sauce straight away, or let it cool down and store it in an airtight container in the fridge.

It will last refrigerated for a couple of days, so you can make it in advance in preparation for a special low-carb dinner.

To reheat, you can microwave it on medium power until hot, removing from the microwave every minute or so to stir it so it heats evenly.

Or, transfer to a pan and reheat it on the stove. The sauce will be thicker after reheating. Which will make it even tastier!

Creamy keto mushroom sauce spooned over pink sirloin steak.

Keto Creamy Mushroom Sauce

5 from 2 votes
This creamy mushroom & mustard sauce with garlic and butter is silky, rich and bursting with flavor! The perfect side dish for a keto & low-carb steak dinner!
Author: Pris Frank
Prep Time 5 minutes
Cook Time 15 minutes
Total Time 20 minutes
Course Side Dish
Cuisine European
Servings 4 servings


  • 3 tablespoons (42 g) butter divided
  • 1 small onion finely chopped
  • 3 to 4 garlic cloves minced
  • 16 ounces (454 g) mushrooms sliced
  • ¾ teaspoon salt
  • 1 teaspoon ground black pepper
  • 2 teaspoons mustard powder or 1 tablespoon Dijon mustard
  • 2 teaspoons dried thyme
  • 1 cup (240 g) heavy cream


  • Heat up a large skillet with half the amount of butter, add the chopped onions and sauté in medium heat until translucent.
  • Add the garlic, and cook until golden.
  • Add the remaining butter, and when it's melted, the mushrooms, salt, black pepper and mustard. Bring heat to low.
  • Cook mushrooms until soft – about 5 to 7 minutes. They will release water, and absorb flavor.
  • Add heavy cream and thyme and simmer, stirring regularly, for about 5 minutes until the sauce thickens.
  • Adjust spices to taste before serving.


Serve creamy mushroom sauce spooned over steaks or other protein, like chicken breasts or roasted turkey. It’s also great with grilled, steamed or air fried vegetables.
See post for instructions on choosing the best mushrooms and making it ahead/reheating.


Serving: 4Calories: 338kcalCarbohydrates: 6.9gProtein: 5.2gFat: 32gFiber: 1.4gSugar: 4.7gNet Carbohydrates: 5.5g
Tried this recipe?Leave a comment and let us know how it was!

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