Cowboy Butter Broccoli Flank Steak: 5-Ingredient Crockpot Dinner Step-by-step instructions

Before you start

Before you start, slice the flank steak thinly against the grain—this is key for tenderness. Cut the broccoli into small, even florets and slice the mushrooms.

If using a store-bought garlic-herb butter, let it soften slightly so it's easy to dot over the top. Have your slow cooker ready and all ingredients measured. No need to preheat or brown anything—this is a true dump-and-go recipe.

Instructions

Layer and Cook

1. 1Layer the Ingredients
   Place the thinly sliced flank steak strips in the bottom of a 6-quart slow cooker. Scatter the broccoli florets and sliced baby bella mushrooms evenly over the beef. Dot the top with the garlic-herb cowboy butter, then sprinkle the au jus gravy mix over everything. Do not stir.
   Look for The beef is covered with a colorful layer of broccoli, mushrooms, butter, and seasoning mix.
   Tip Slicing the steak thinly against the grain helps it become tender during the long, slow cook.
2. 2Cook Low and Slow
   Cover the slow cooker and cook on LOW for 6 to 8 hours, or on HIGH for 3 to 4 hours, until the beef is fork-tender and the broccoli is as soft as you like. The butter will melt into the au jus, creating a rich, golden sauce. Let it rest for 3 minutes before slicing.
   Look for The sauce is bubbling gently and the beef shreds easily with a fork.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip For the most tender beef, choose LOW and the longer end of the range. Stir gently once halfway if desired, but it's not necessary.
3. 3Rest the Beef
   Turn off the slow cooker and let the beef rest in the hot sauce for at least 3 minutes. This allows the juices to redistribute, keeping the meat moist and tender.
   Look for The beef rests in the bubbling sauce, absorbing extra flavor.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Resting is especially important for lean cuts like flank steak—don't skip it.

At the end of this phase, the slow cooker is filled with raw beef, broccoli, mushrooms, butter, and au jus mix. As it cooks, the butter melts and the sauce begins to bubble.

The aroma of garlic and herbs fills the kitchen. The beef should be fork-tender and the vegetables soft. Check that the beef is fully cooked and the sauce is rich and golden before moving on.

Scoop and Serve

4. 4Scoop and Serve
   Using a serving spoon, lift a generous portion of the beef, broccoli, and mushrooms from the slow cooker, letting the sauce cling to each piece. Pile the mixture over a bed of creamy whipped mashed potatoes, then spoon extra au jus over the top.
   Look for The serving spoon comes up loaded with tender beef and vegetables in a glossy, golden sauce.
   Tip Mashed potatoes are the perfect partner, but the dish is also delicious over rice or egg noodles.

When you lift the lid, you'll see a bubbling, golden sauce with tender beef and vegetables. The beef should shred easily with a fork, and the broccoli should be tender but still bright green. The sauce should be glossy and aromatic. Scoop a generous portion onto plates with mashed potatoes, making sure to get plenty of sauce.

Enjoy

5. 5Finish and Enjoy
   Serve immediately while hot. The beef should be fork-tender, the broccoli tender but with a little bite, and the sauce rich and buttery. Add a sprinkle of fresh cracked pepper if desired (not shown).
   Look for Steam rises from the plate, and the sauce glistens over the beef and potatoes.
   Tip This is a one-dish meal—no need for extra sides.

The final dish is a beautiful pile of tender beef and vegetables over creamy mashed potatoes, all coated in a buttery au jus. The steam rises, and the first bite is rich, savory, and satisfying. The beef is melt-in-your-mouth, the broccoli and mushrooms are perfectly cooked, and the sauce is the star. Serve immediately and enjoy every bite.

Common mistakes

One common mistake is slicing the steak with the grain, which makes it chewy. Always slice against the grain. Another is overcrowding the slow cooker—if you have more than 2 pounds of beef, use a larger slow cooker or cook in batches.

Also, resist the urge to stir too often; lifting the lid releases heat and slows cooking. Finally, don't add extra liquid—the beef and vegetables release plenty of moisture, and the butter and au jus create enough sauce.

How to tell it’s done

The dish is done when the beef is fork-tender and easily pulls apart—this usually takes 6 to 8 hours on LOW or 3 to 4 hours on HIGH. The broccoli should be tender but not mushy; it will soften more as it sits in the hot sauce.

The sauce should be bubbling and slightly thickened. For safety, the beef must reach an internal temperature of at least 145°F (63°C), but at this point it will be well above that.

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