Dinner

Vegetable and Sausage Breakfast Casserole Recipe

BySophie Carsel January 29, 2026January 29, 2026

Introduction

This hearty breakfast casserole is packed with savory veggie sausages, mushrooms, and vibrant red peppers, all bound together by a rich egg and cheddar mixture. It’s a perfect dish to prepare ahead for a weekend brunch or a comforting weekday breakfast.

The image shows a white rectangular dish filled with a baked egg casserole, with one corner scooped out. The casserole has visible layers of browned eggs mixed with round slices of browned sausage, red bell pepper strips, sliced mushrooms, and bits of green herbs spread evenly throughout. A square portion of the casserole is placed on a white round plate next to the dish, revealing similar layers with sausage, red pepper, mushrooms, and chopped fresh green herbs sprinkled on top. A spoon rests on the plate, partially under the casserole. The scene is set on a white marbled surface with a light pink cloth with frayed edges partially underneath the dish and plate, and a small dark green round ornament lies beside the plate. photo taken with an iphone --ar 4:5 --v 7

Ingredients

250g chestnut mushrooms, sliced
1½ tbsp vegetable oil, plus extra for the tin (optional)
6 veggie sausages, sliced into bite-sized pieces
1 large red onion, finely sliced
2 red peppers, deseeded and sliced
8 eggs
250ml whole milk
125g cheddar, grated
10g chives, finely sliced

Instructions

Step 1: Preheat your oven to 200°C (180°C fan/gas mark 6). In a large non-stick frying pan over medium-high heat, fry the mushrooms until their liquid has released and evaporated, about 8-10 minutes. Add ½ tablespoon vegetable oil and cook until golden, about 2 minutes. Remove mushrooms and place in a large bowl.
Step 2: Wipe out the pan and return it to medium heat. Add the remaining 1 tablespoon of oil and fry the veggie sausages until golden all over. Remove them with a slotted spoon and add to the bowl with the mushrooms.
Step 3: In the same pan, fry the red onion and red peppers for 8-10 minutes, stirring occasionally, until soft but not browned. Add these to the bowl with sausages and mushrooms, then mix everything well. Season generously with salt and pepper.
Step 4: Transfer the sausage and vegetable mixture into a baking dish (approximately 35 x 25 cm) or roasting tin. If using a tin, lightly oil it to prevent sticking.
Step 5: In a large jug, whisk together the eggs, whole milk, grated cheddar, and chives. Season the mixture, then pour it evenly over the vegetables and sausages in the baking dish.
Step 6: Bake in the preheated oven for 25-30 minutes, or until the casserole is golden on top and set in the middle. Allow it to cool slightly before cutting into squares and serving.

Tips & Variations

For extra flavor, try adding a pinch of smoked paprika or herbs such as thyme to the vegetable mixture.
You can substitute veggie sausages with cooked plant-based mince or crumbled tofu for a different texture.
Use a mixture of cheeses like mozzarella or Monterey Jack for a meltier finish.
This casserole can be prepared a day in advance and baked fresh in the morning for convenience.

Storage

Store leftover casserole covered in the refrigerator for up to 3 days. Reheat gently in the oven at 160°C until warmed through, or microwave in short bursts to avoid drying out. This dish can also be frozen; defrost completely before reheating.

How to Serve

A white rectangular baking dish filled with a baked egg dish that has three main visible layers: a golden-yellow egg base, scattered slices of browned sausage, and red pepper strips on top. There are also pieces of mushrooms and sliced red onions mixed throughout the dish, along with green herbs sprinkled across the surface. Next to the dish, a portion is served on a white round plate, showing the same layers clearly with chunks of browned sausage, red bell peppers, mushrooms, and finely chopped green herbs. A metal spoon rests on the plate beside the food, and the setting includes a soft pink napkin under the baking dish on a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use a different type of sausage?

Yes, you can swap veggie sausages for your preferred variety, including meat-based sausages if you’re not vegetarian. Just ensure they are cooked before assembling the casserole.

Is this casserole suitable to prepare ahead of time?

Absolutely. You can assemble the casserole the night before, cover it and keep it in the fridge, then bake it fresh in the morning. This makes for a convenient and stress-free breakfast.