Slow-Cooker Mushroom Onion Butter Pot Roast Step-by-step instructions

Before you start

Before you start, make sure you have a 6-quart slow cooker. There's no need to brown the beef or sauté the mushrooms—everything goes into the pot raw. Take the beef out of the refrigerator and pat it dry with paper towels.

If the roast is tied with butcher's twine, leave it as is; it will hold together during cooking. Halve the mushrooms if they're large. Measure out the onion soup mix and have the butter ready. That's it—you're ready to go.

Instructions

Layer and Top

1. 1Prep the Roast and Vegetables
   Place the beef bottom round roast in the center of a 6-quart slow cooker. Sprinkle the dry onion soup mix evenly over the top of the roast. Scatter the halved cremini mushrooms around the sides of the roast, tucking them into the corners of the slow cooker.
   Look for The roast is centered, with the soup mix coating the top and mushrooms nestled around.
   Tip No need to sear the roast—the slow cooker does all the work.
2. 2Add the Butter
   Place the whole stick of salted butter directly on top of the seasoned roast. It will melt as the slow cooker heats, basting the meat and creating a rich, savory jus.
   Look for The butter sits squarely on the roast, ready to melt.
   Tip For even melting, you can slice the butter into pats, but a whole stick works fine.

At the end of this phase, the raw roast sits in the slow cooker, dusted with onion soup mix and surrounded by halved mushrooms.

A stick of butter rests on top, ready to melt. The scene is simple but promising—the ingredients are in place, and the slow cooker is about to work its magic.

Cook Low and Slow

3. 3Cook Low and Slow
   Cover the slow cooker and cook on LOW for 8 to 10 hours, until the beef is fork-tender and easily shreds. The internal temperature of the roast should reach at least 145°F (63°C) for safety, but for pot roast, cook until it's much more tender. Let it rest for 3 minutes before slicing.
   Look for The aroma of onions and butter fills the kitchen as the roast simmers.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Resist the urge to lift the lid—each peek lets out heat and adds cooking time.
4. 4Check for Tenderness
   After 8 hours, check the roast by inserting a fork into the thickest part. It should slide in with little resistance, and the meat should begin to pull apart. If not, continue cooking for another 1 to 2 hours. Let it rest for 3 minutes before slicing.
   Look for The fork goes in easily and the meat starts to shred.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip If the liquid looks too thin, you can remove the roast and simmer the jus on the stovetop to reduce.
5. 5Rest the Roast
   Turn off the slow cooker and let the roast rest in the liquid for at least 10 minutes. This allows the juices to redistribute, making the meat even more tender and flavorful.
   Look for The roast rests in the bubbling jus, absorbing flavor.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Resting is essential for a moist, tender result.

After 8 hours, the kitchen smells deeply savory, with notes of onion and butter. The roast is submerged in a golden, bubbling jus, and the mushrooms have softened and darkened. A fork inserted into the meat meets no resistance, and the surface of the roast is glossy and tender.

Shred and Serve

6. 6Shred and Serve
   Using two forks, shred the beef directly in the slow cooker, mixing it with the mushrooms and jus. Serve the hot beef and mushrooms over mashed potatoes or egg noodles, spooning extra jus over the top. Let it rest for 3 minutes before slicing.
   Look for The beef shreds easily and soaks up the golden jus.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Taste and add salt or pepper if needed—the soup mix and butter already add plenty of flavor.

The shredded beef is moist and glistening, coated in a rich, buttery jus. The mushrooms are tender and flavorful, and the whole dish is steaming and ready to be served. The texture is fork-tender, and the aroma is irresistible.

Common mistakes

One common mistake is lifting the lid to check on the roast too often. Every time you open the slow cooker, heat escapes, which can add up to 30 minutes of extra cooking time. Another mistake is using a lean cut of beef and cooking it too long—this can dry it out.

Stick to tougher cuts like bottom round or chuck. Finally, don't skip the resting step—letting the roast rest in the juices for 10 minutes before shredding ensures it stays moist.

How to tell it’s done

The roast is done when it's fork-tender. Insert a fork into the thickest part of the meat—it should slide in with no resistance, and the meat should easily pull apart.

The internal temperature should reach at least 145°F (63°C) for food safety, but for optimal tenderness, you'll want to cook it longer, until it shreds easily. This typically takes 8 to 10 hours on LOW. If the meat is still tough, continue cooking and check every 30 minutes.

• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest