If you love a savory breakfast that feels cozy, satisfying, and packed with flavor, this High Protein Herby Sourdough Breakfast Casserole needs to happen. It has everything you want in one pan: golden sourdough, fluffy eggs, sharp cheddar, sweet sautéed leeks, fresh dill, parsley, and a creamy custard base boosted with cottage cheese for extra protein.
It feels elevated enough for brunch, practical enough for meal prep, and delicious enough to make on repeat.
Why You’ll Love This Recipe
Flavor + Texture
This casserole bakes up tall and golden with crisp cheesy edges, a fluffy center, and tender sourdough pockets that soak up all the savory flavor. The leeks become soft and slightly sweet, while the dill and parsley brighten every bite.
Sharp cheddar adds richness and depth, and the Dijon mustard quietly enhances the cheesy flavor without tasting like mustard.
High Protein + Balanced
Thanks to eggs, cottage cheese, and cheddar, this breakfast casserole is naturally high in protein to help keep you full and satisfied. It’s a great option for busy mornings, hosting brunch, or prepping breakfast ahead for the week.
Great for Meal Prep
Slice it into squares and reheat throughout the week. It holds together beautifully once cooled and tastes just as good the next day.
Ingredient Notes
- Sourdough bread: Slightly stale or toasted cubes work best so the casserole stays structured and not soggy.
- Leeks: Add mild onion flavor with a natural sweetness. Be sure to wash well.
- Cottage cheese: Blends into the custard and adds creaminess plus extra protein.
- Sharp cheddar: Gives bold flavor and a beautiful golden top.
- Fresh dill + parsley: Make the casserole taste fresh and vibrant.
- Dijon mustard: Optional but highly recommended for flavor depth.
Bread Options
- Whole grain bread
- Gluten-free sandwich bread
- Ciabatta or baguette
- English muffins, cubed
Cheese Options
- White cheddar
- Gruyère
- Mozzarella for a milder version
- Feta for a tangy twist
Vegetable Options
- Spinach
- Mushrooms
- Asparagus
- Bell peppers
- Green onions instead of leeks
Storage
Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat individual slices in the microwave or oven.
You can also freeze slices individually and reheat as needed.
Perfect For
- Weekend brunch
- Postpartum meal prep
- Holiday mornings
- Hosting guests
- Protein-packed weekday breakfasts
Are you going to make my High Protein Herby Sourdough Breakfast Casserole?!
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Ingredients
Method
- Preheat oven to 375°F. Grease an 8×8 baking dish.
- Heat butter or oil in a skillet. Sauté leeks 6–8 minutes until softened. Add garlic and cook 30 seconds.
- Add bread cubes to dish. Scatter in leek mixture, dill, parsley, and 3/4 cup cheddar.
- Blend eggs, cottage cheese, milk, Dijon, salt, and pepper until smooth.
- Pour mixture evenly over bread. Press bread down gently and let soak 10–15 minutes.
- Top with remaining cheddar.
- Bake 40 minutes and rest 10–15 minutes before slicing.
Notes
6 servings
Calories: ~320
Protein: ~23g
Carbs: ~22g
Fat: ~15g
