Dinner · Part 3 of 3: Tips & recipe card

Slow-Cooker Portobello Garlic Butter Beef Brisket Tips, FAQ & printable recipe

Name: Slow-Cooker Portobello Garlic Butter Beef Brisket
Prep time: 15 min
Cook time: 8 h
Total time: 8 h 25 min
Cuisine: American
Ingredients: 3 1/2 lb beef brisket, trimmed; 8 oz portobello mushrooms, thickly sliced; 2 tbsp minced garlic; 4 tbsp garlic-herb compound butter (cowboy butter), cut into medallions

By Clara Weller · Oct 28, 2026

Slow-cooker beef brisket with portobello mushrooms and garlic butter gravy in a black crockpot

Prep: 15 min
Cook: 8 h
Total: 8 h 25 min
Serves: 8

Includes 10 min resting

Tips for success

For the best flavor, sear the brisket in a hot skillet before adding it to the slow cooker. This adds a deep, caramelized crust that enhances the overall taste.

However, the recipe is still delicious without this step—just skip it for a truly dump-and-go meal. If you have time, searing is worth the extra few minutes.

To make the gravy thicker, remove the brisket and mushrooms from the slow cooker, then whisk a cornstarch slurry (1 tablespoon cornstarch mixed with 2 tablespoons cold water) into the remaining juices.

Cook on HIGH for 10-15 minutes until thickened. This creates a luscious sauce perfect for spooning over the meat and noodles.

Variations

Add Onions and Peppers: Layer sliced onions and bell peppers over the brisket before adding the mushrooms. They'll soften and sweeten as they cook, adding extra flavor to the gravy.
Use Different Mushrooms: Substitute cremini or baby bella mushrooms for portobellos. They have a similar earthy flavor and hold up well during long cooking.
Make It Spicy: Add a pinch of red pepper flakes or a chopped jalapeño to the garlic for a subtle kick. The heat balances the richness of the butter and beef.
Herb Variation: If you don't have compound butter, mix softened butter with fresh or dried herbs like rosemary, thyme, and oregano. Adjust the herbs to your preference.

Storage and make-ahead

Fridge: Store leftover brisket and gravy in an airtight container in the refrigerator for up to 4 days. Reheat gently, adding a splash of broth if needed.
Freezer: Freeze leftover brisket and gravy in a freezer-safe container for up to 3 months. Thaw overnight in the refrigerator before reheating.
Reheat: Reheat the brisket gently on the stovetop or in the microwave, adding a splash of beef broth to keep it moist. Warm until heated through.

Store leftover brisket and gravy in an airtight container in the refrigerator for up to 4 days. The flavors will continue to meld, making it even more delicious the next day. Reheat gently on the stovetop or in the microwave, adding a splash of beef broth if needed to loosen the gravy.

This dish is perfect for making ahead. Cook the brisket as directed, then let it cool completely before storing in the refrigerator. It can be made up to 2 days in advance. Reheat gently on the stovetop or in a 350°F (175°C) oven until warmed through. The brisket tastes even better the next day as the flavors meld.

Serving ideas

Serve the shredded brisket over warm buttered egg noodles, mashed potatoes, or creamy polenta. Spoon plenty of the mushroom-garlic-butter gravy over the top.

A sprinkle of fresh parsley or chives adds a pop of color and freshness. This hearty dish pairs well with a simple green salad or roasted vegetables for a complete meal.

For a low-carb option, serve the brisket over cauliflower rice or alongside steamed broccoli. The savory gravy makes it satisfying on its own.

Leftovers are great in sandwiches or tacos—just pile the meat on toasted bread or warm tortillas and add a little cheese. However you serve it, this brisket is sure to become a family favorite.

Frequently asked questions

Can this brisket be made in an Instant Pot?

Yes, but cooking times will differ. Sear the brisket using the sauté function, then add the mushrooms, garlic, and butter. Pressure cook on HIGH for about 60-70 minutes, then let the pressure release naturally for 15 minutes before shredding. Check for tenderness and cook longer if needed.

What is the best cut of beef for this recipe?

Beef brisket is ideal because it becomes incredibly tender when slow-cooked. You can also use chuck roast or bottom round, which have similar marbling and benefit from long, moist cooking. Just adjust the cooking time as needed.

How can the gravy be thickened?

To thicken the gravy, remove the meat and mushrooms from the slow cooker. Whisk 1 tablespoon of cornstarch with 2 tablespoons of cold water, then stir into the juices. Cook on HIGH for 10-15 minutes until thickened. Alternatively, simmer the juices on the stovetop to reduce.

Can this recipe be doubled?

Yes, but ensure your slow cooker is large enough (at least 7 quarts). Adjust the cooking time slightly, as a larger volume may take longer. Check for tenderness with a fork before serving.

What sides go well with this brisket?

This brisket is delicious over buttered egg noodles, mashed potatoes, or polenta. It also pairs well with roasted vegetables, a green salad, or crusty bread to soak up the gravy. For a low-carb option, serve with cauliflower rice or steamed greens.

Recipe card

Slow-Cooker Portobello Garlic Butter Beef Brisket

Prep 15 minCook 8 hRest 10 minTotal 8 h 25 minServes 8

Ingredients

3 1/2 lb beef brisket, trimmed
8 oz portobello mushrooms, thickly sliced
2 tbsp minced garlic
4 tbsp garlic-herb compound butter (cowboy butter), cut into medallions

Instructions

Place the trimmed beef brisket flat in the bottom of a 6- to 7-quart slow cooker. If needed, cut the brisket to fit, but keep it in large pieces.
Scatter the thickly sliced portobello mushrooms over the brisket, then sprinkle with the minced garlic. Spread them evenly so they cover the meat.
Place the garlic-herb compound butter medallions on top of the mushrooms and garlic. Distribute them evenly so they melt over the meat as it cooks.
Cover the slow cooker and cook on LOW for 8 to 10 hours, or on HIGH for 5 to 6 hours, until the brisket is fork-tender and easily shreds. Let it rest for 3 minutes before slicing.
Turn off the slow cooker and let the brisket rest in the juices for at least 10 minutes. This allows the meat to reabsorb moisture and makes shredding easier.
Use two forks to shred the brisket directly in the slow cooker, mixing it with the mushrooms and buttery gravy. Serve over warm buttered egg noodles or as desired. Let it rest for 3 minutes before slicing.

Contains: milk

Estimated nutrition per serving

Calories: 480
Protein: 35 g
Carbohydrates: 5 g
Fat: 35 g

Automatic estimate from the ingredient list, not laboratory-verified.

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This recipe is based on a short cooking video and is published under the pen name Clara Weller. It was checked before publication, but errors can slip through. Nutrition, when shown, is an estimate. Read more in our editorial policy and on our food safety page.