Photo of Mushroom-and-Swiss potato breakfast casserole by WW

Mushroom-and-Swiss potato breakfast casserole

Total Time
7 hr 30 min
30 min
7 hr
This dish was made for weekend breakfasts and brunch. It is prepared in the slow cooker, which means you can put it together the night before, let it cook while you sleep, and wake up to a savory, satisfying breakfast that requires minimal effort in the morning. Hash browns are layered with an herbed onion, garlic, and mushroom mixture and cheese and covered with a seasoned egg mixture. Cremini mushrooms are available in most grocery stores, but if you can’t find them, use whatever mushroom variety that you like. Pair this casserole with fresh fruit—you can buy the precut container in the produce department—for a breakfast that is worth waking up for.


Cooking spray

4 spray(s)

Uncooked onion

4 medium, thinly sliced

Cremini mushroom

32 oz, sliced (four 8-oz packages)

Kosher salt

1½ tsp, divided

Black pepper

½ tsp, divided


3 large clove(s), minced


1 Tbsp, fresh, minced

Frozen shredded hash brown potatoes

20 oz, or refrigerated variety

Shredded low fat Swiss cheese

2 cup(s)


12 large egg(s)

1% low fat milk

1½ cup(s), 1% variety

Dijon mustard

2 Tbsp, grainy variety


1 Tbsp, for garnish


  1. Coat a large nonstick skillet with cooking spray; heat over medium-high heat. Add onions, mushrooms, 1/2 tsp salt, and 1/4 tsp pepper; cook, stirring often, until vegetables soften, 10 minutes. Stir in garlic and rosemary; cook, stirring, 1 more minute.
  2. Coat inside of a 6-qt slow cooker with cooking spray. Place third of potatoes in bottom; top with half vegetable mixture and 2/3 c cheese. Repeat layers with another third of potatoes, remaining vegetables and 2/3 cup cheese; top with remaining potatoes.
  3. In a medium bowl, whisk together eggs, milk, mustard, remaining 1 tsp salt, and remaining 1/4 tsp pepper; pour over casserole in slow cooker and sprinkle with remaining cheese. Cover and cook on low 6-7 hours. Serve sprinkled with chopped chives.
  4. Serving size: 1 cup