There’s a certain magic to a morning that doesn’t involve a frantic scramble for breakfast. For years, my weekday mornings were a blur of toast, cereal, and a nagging feeling that we weren’t starting our day with the fuel we really needed. I wanted something substantial, something that would keep us all going until lunchtime without a mid-morning slump, which is also the goal of our 20 High Protein Low Carb Snacks For A Healthy Diet. That’s when I dedicated myself to perfecting the ultimate make-ahead breakfast, and this High Protein Breakfast Casserole was the delicious result.

This isn’t just a recipe; it’s a strategy for calmer mornings and better days. The beauty of this dish is its prepare-ahead nature. You can assemble it the night before, or even bake it on a Sunday afternoon, and simply reheat slices for a satisfying breakfast all week long. It’s built around wholesome, protein-rich ingredients like eggs, lean sausage, and cottage cheese (my secret for an unbelievably creamy texture!) that provide lasting energy.

I make this at least once a week – it’s become a family favourite that everyone looks forward to. It bridges the gap between a hearty weekend brunch and a practical weekday meal, offering a savoury, satisfying start to any day. It’s the kind of dish that makes you feel organised and nourished, all before your second cup of tea.

Recipe Overview

• Prep Time: 20 minutes
• Cook Time: 45-50 minutes
• Total Time: 1 hour 10 minutes
• Servings: 8-10 slices
• Difficulty: Straightforward

Why You’ll Love This High Protein Breakfast Casserole (Make-Ahead Breakfast)

• Sustained Energy: Packed with eggs, sausage, and cheese, each slice delivers a substantial protein hit that helps keep you full and focused throughout the morning.
• Super Convenient for Meal Prep: This is the ultimate make-ahead breakfast. Bake it once and enjoy delicious, ready-to-heat breakfasts for several days. It saves so much time on busy mornings.
• Endlessly Customisable: Think of this recipe as a brilliant template. You can swap the vegetables, use different cheeses, or try another protein. It’s a fantastic way to use up leftover veg from the fridge.
• Rich and Savoury Flavour: The combination of savoury sausage, sautéed vegetables, sharp cheddar, and creamy eggs creates a wonderfully deep and satisfying flavour profile that feels like a treat.
• Feeds the Whole Family: This recipe yields a generous casserole, making it ideal for feeding a family or for having guests over for a relaxed brunch. Friends always ask me for this recipe after trying it!

High Protein Breakfast Casserole (Make-Ahead Breakfast)

15 min prep  ·  65 min cook  ·  8 servings

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Ingredients You’ll Need

• 1 tbsp olive oil
• 1 large onion, finely chopped
• 1 red bell pepper, deseeded and diced
• 400g lean pork or turkey sausages, casings removed
• 150g fresh spinach
• 12 large free-range eggs
• 250g full-fat cottage cheese
• 120ml whole milk
• 1 tsp Dijon mustard
• 1/2 tsp smoked paprika
• 1/2 tsp dried oregano
• 200g mature cheddar cheese, grated
• 50g Parmesan cheese, finely grated
• Salt and freshly ground black pepper, to taste
• A handful of fresh chives, finely chopped (for garnish)

Tip: For the best flavour, choose good-quality sausages from a local butcher. The seasoning in the sausage meat provides a fantastic base flavour for the entire casserole, so it’s worth getting the good stuff!

How to Make High Protein Breakfast Casserole (Make-Ahead Breakfast)

1. Preheat and Prepare: First, preheat your oven to 180°C (160°C Fan/Gas Mark 4). Lightly grease a 9×13 inch (or similar size) baking dish with a little butter or oil.
2. Sauté the Vegetables and Sausage: Heat the olive oil in a large frying pan over a medium heat. Add the chopped onion and red pepper and cook for 5-7 minutes, until softened. Add the sausage meat to the pan, breaking it up with a wooden spoon. Cook for another 8-10 minutes, until the sausage is browned and cooked through.
3. Wilt the Spinach: Add the fresh spinach to the pan in handfuls, allowing it to wilt down before adding more. Cook for just a minute or two until all the spinach has wilted. Drain any excess liquid from the pan – this is key to avoiding a soggy casserole.
4. Create the Egg Mixture: In a large mixing bowl, whisk the 12 eggs together. Add the cottage cheese, milk, Dijon mustard, smoked paprika, and oregano. Whisk until everything is well combined. Don’t worry if the cottage cheese remains a little lumpy. Season generously with salt and pepper.
5. Combine and Assemble: Stir most of the grated cheddar and all of the Parmesan into the egg mixture, reserving a small handful of cheddar for the top. Gently fold the cooked sausage and vegetable mixture into the egg base.
6. Pour and Bake: Pour the entire mixture into your prepared baking dish and spread it out into an even layer. Sprinkle the remaining cheddar cheese over the top.
7. Bake to Perfection: Place the dish in the preheated oven and bake for 45-50 minutes. The casserole is ready when the centre is set (a knife inserted into the middle should come out clean) and the top is golden brown and puffy.
8. Rest and Serve: Allow the casserole to cool in the dish for at least 10 minutes before slicing. This helps it to set properly, making it much easier to cut into clean squares. Garnish with fresh chives before serving.

Tips From My Kitchen

• Don’t Skip Draining: After cooking your sausage and vegetables, make sure to drain off any excess fat or water. This simple step is the secret to a firm, sliceable casserole rather than a watery one.
• Let It Rest: I know it’s tempting to dive right in, but letting the casserole rest for 10-15 minutes after it comes out of the oven is crucial. It allows the eggs to finish setting up, ensuring perfect slices every time.
• Room Temperature Ingredients: If you have the time, letting your eggs and milk come to room temperature before whisking can result in a slightly more tender and evenly cooked casserole.
• Cheese Choices: While mature cheddar is fantastic, feel free to experiment! A mix of Gruyère and cheddar adds a lovely nutty depth, or a bit of crumbled feta can add a salty tang.

Equipment You’ll Need

• 9×13 inch baking dish
• Aluminium foil
• Mixing bowls
• Sharp knife

Delicious Variations to Try

• Spicy Version: To add a bit of a kick, add one finely chopped red chilli or a teaspoon of chilli flakes to the pan along with the onions and peppers. A spicy chorizo instead of regular sausage also works beautifully.
• Vegetarian Option: This casserole is easily made vegetarian. Simply omit the sausage and replace it with 200g of sautéed mushrooms and 100g of crumbled feta cheese. You could also use a quality plant-based sausage.
• Different Protein: Don’t have sausage? No problem. Use 300g of diced cooked ham, crispy bacon bits, or even shredded leftover chicken. It’s a versatile recipe, much like my Hobo Casserole With Ground Beef, which is great for using what you have.

What to Serve With High Protein Breakfast Casserole (Make-Ahead Breakfast)

This casserole is a complete meal on its own, but if you’re serving it for a larger brunch, here are a few ideas:

• Sliced avocado with a sprinkle of sea salt
• A simple green salad with a lemon vinaigrette
• Toasted sourdough or rye bread
• A bowl of fresh berries or a fruit salad

Frequently Asked Questions

High Protein Breakfast Casserole (Make-Ahead Breakfast)

A hearty and flavorful make-ahead breakfast casserole packed with sausage, vegetables, eggs, and cheese, perfect for a high-protein start to the day.

Print Recipe
Pin Recipe

Prep Time 15 minutes mins

Cook Time 1 hour hr 5 minutes mins

Total Time 1 hour hr 20 minutes mins

Servings: 8 servings

Course: Breakfast

Cuisine: American

Calories: 350

Ingredients
Method
Notes

Ingredients

  

• 1 tbsp olive oil
• 1 large onion finely chopped
• 1 red bell pepper deseeded and diced
• 400 g lean pork or turkey sausages casings removed
• 150 g fresh spinach
• 12 large free-range eggs
• 250 g full-fat cottage cheese
• 120 ml whole milk
• 1 tsp Dijon mustard
• 1/2 tsp smoked paprika
• 1/2 tsp dried oregano
• 200 g mature cheddar cheese grated
• 50 g Parmesan cheese finely grated
• Salt and freshly ground black pepper to taste
• A handful of fresh chives finely chopped (for garnish)

Method

 

1. Preheat and Prepare: First, preheat your oven to 180°C (160°C Fan/Gas Mark 4). Lightly grease a 9×13 inch (or similar size) baking dish with a little butter or oil.
2. Sauté the Vegetables and Sausage: Heat the olive oil in a large frying pan over a medium heat. Add the chopped onion and red pepper and cook for 5-7 minutes, until softened. Add the sausage meat to the pan, breaking it up with a wooden spoon. Cook for another 8-10 minutes, until the sausage is browned and cooked through.
3. Wilt the Spinach: Add the fresh spinach to the pan in handfuls, allowing it to wilt down before adding more. Cook for just a minute or two until all the spinach has wilted. Drain any excess liquid from the pan – this is key to avoiding a soggy casserole.
4. Create the Egg Mixture: In a large mixing bowl, whisk the 12 eggs together. Add the cottage cheese, milk, Dijon mustard, smoked paprika, and oregano. Whisk until everything is well combined. Don’t worry if the cottage cheese remains a little lumpy. Season generously with salt and pepper.
5. Combine and Assemble: Stir most of the grated cheddar and all of the Parmesan into the egg mixture, reserving a small handful of cheddar for the top. Gently fold the cooked sausage and vegetable mixture into the egg base.
6. Pour and Bake: Pour the entire mixture into your prepared baking dish and spread it out into an even layer. Sprinkle the remaining cheddar cheese over the top.
7. Bake to Perfection: Place the dish in the preheated oven and bake for 45-50 minutes. The casserole is ready when the centre is set (a knife inserted into the middle should come out clean) and the top is golden brown and puffy.
8. Rest and Serve: Allow the casserole to cool in the dish for at least 10 minutes before slicing. This helps it to set properly, making it much easier to cut into clean squares. Garnish with fresh chives before serving.

Notes

It is crucial to drain any excess liquid from the cooked sausage and vegetable mixture to avoid a soggy casserole. The casserole should rest for at least 10 minutes after baking to set properly before slicing.

I truly hope this High Protein Breakfast Casserole helps make your mornings a little easier and a lot more delicious. It’s a staple in my kitchen for a reason, and I’m so excited to share it with you. If you give it a try, please let me know what you think in the comments below. I love hearing about your own variations!

High Protein Breakfast Casserole (Make-Ahead Breakfast) Your new favorite healthy meal prep.

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