Slow Cooker Breakfast Casserole
Servings: 8 servings
Calories: 439kcal
Make-ahead slow cooker breakfast casserole with hash browns, eggs, spinach, mushrooms, and cheese. 25 minutes prep, cooks overnight, feeds 8.
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Equipment
Ingredients
For the base:
- 10 oz frozen spinach thawed and squeezed very dry
- 1 tablespoon olive oil
- 8 oz cremini mushrooms sliced
- 1 medium yellow onion finely diced
- 32 oz hash brown potatoes shredded or diced
- 1 medium red bell pepper diced
- 1 medium green bell pepper diced
- 2½ cups shredded sharp cheddar cheese divided
For the egg mixture:
- 12 large eggs
- 8 oz cottage cheese about 1 cup
- 1 cup whole milk
- 1½ teaspoons dry mustard
- 1 teaspoon kosher salt
- 1 teaspoon garlic powder
- ½ teaspoon smoked paprika
- ½ teaspoon black pepper
For serving:
- 2 green onions thinly sliced
- sour cream optional
- salsa or hot sauce, optional
- fresh chives chopped (optional)
Instructions
Prep the vegetables:
- Thaw frozen spinach and squeeze very dry using a clean kitchen towel or paper towels. This is important—excess moisture makes the casserole watery. Set aside.
- Heat the olive oil in a large skillet over medium-high heat. Add the mushrooms and cook 5-6 minutes, stirring occasionally, until golden brown and moisture has evaporated. Add the onion and cook another 3-4 minutes until softened. Remove from heat and let cool slightly.
Prepare the slow cooker:
- Grease a 6-quart slow cooker with cooking spray or butter.
- In a blender, combine the eggs, cottage cheese, milk, dry mustard, salt, garlic powder, smoked paprika, and black pepper. Blend until completely smooth, about 30 seconds. No cottage cheese curds should remain.
Layer and cook:
- Spread half the hash browns in the bottom of the slow cooker. Top with half the mushroom-onion mixture, half the spinach, half the bell peppers, and 1 cup of the cheese.
- Repeat layers: remaining hash browns, mushroom-onion mixture, spinach, bell peppers, and 1 cup cheese. Do not stir.
- Pour the egg mixture evenly over the layered ingredients. Gently press down with a spatula to ensure the egg mixture reaches the bottom.
- Cover and cook on LOW for 7-8 hours or HIGH for 3-4 hours, until eggs are set and edges are golden.
- Sprinkle the remaining ½ cup cheese over the top. Turn off the slow cooker, cover, and let rest 15 minutes. The cheese will melt and the casserole will firm up for easier slicing.
- Scoop or slice into 8 portions. Garnish with green onions and serve with sour cream, salsa, or chives if desired.
Notes
- Sauté mushrooms until golden and dry to prevent a watery casserole.
- Squeeze spinach very dry; excess moisture causes a soggy casserole.
- Blend cottage cheese completely smooth for creaminess and added protein.
- Use frozen hash browns directly from the freezer; thawed hash browns get mushy.
- Diced hash browns add more potato texture; shredded ones get crispier edges.
- Do not stir the layers — they create distinct sections when sliced.
- Some liquid around the edges is normal; it absorbs as the casserole rests.
- If the casserole finishes early, switch to WARM for up to 1 hour.
- For a smaller slow cooker (4-quart), reduce all ingredients by half (yields 4 servings).
- Portion into individual containers for grab-and-go breakfasts.
Nutrition
Calories: 439kcal | Carbohydrates: 30g | Protein: 27g | Fat: 24g | Saturated Fat: 11g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 7g | Trans Fat: 0.03g | Cholesterol: 323mg | Sodium: 784mg | Potassium: 876mg | Fiber: 4g | Sugar: 5g | Vitamin A: 5617IU | Vitamin C: 44mg | Calcium: 425mg | Iron: 4mg
