In a large bowl, combine 1 pound Ground beef, 3/4 teaspoon Salt 1/4 teaspoon Black pepper , 3/4 teaspoon Onion powder, 3/4 teaspoon Garlic powder, 1/2 cup Breadcrumbs, and beaten 1 large Egg. Mix gently until just combined, then shape into even patties.
Heat a skillet over medium heat and sear the patties for 2–3 minutes per side until browned. This step adds extra flavor but isn’t necessary if you’re short on time.
In a separate bowl, whisk together cream of m10.5 ounces Cream of mushroom soup, 1/2 cup Beef broth, and 2 teaspoon Worcestershire sauce until smooth.
Place the patties in the slow cooker, then pour the mushroom sauce evenly over the top.
Cover and cook on low for 6–8 hours or high for 3–4 hours, until the patties are cooked through and tender.
If you prefer a thicker sauce, mix 1 teaspoon Cornstarch with 1 teaspoon water and stir into the gravy during the last 15–20 minutes of cooking.
Spoon the Salisbury steak and creamy mushroom sauce over mashed potatoes, rice, or egg noodles. Garnish with fresh parsley if desired.