Low Carb Veggie Breakfast Casserole — High Protein Meal Prep (14g Protein Per Slice)
/If you don't have breakfast prepped on Sunday, you're not eating a good breakfast on Monday. That's the honest reality — the best intentions in the world don't produce a healthy breakfast when you're half-awake trying to leave the house in 20 minutes. This low carb veggie breakfast casserole solves the problem completely.
Make it Sunday. Slice it into 12 pieces. Refrigerate. Every morning for the next four days you grab a slice, microwave it for 60-90 seconds, and you have 14g of protein and a full serving of vegetables in your hands before you've finished your first cup of coffee. The whole casserole takes 10 minutes of active work and 40 minutes in the oven — most of which you are not in the kitchen.
This base recipe uses mushrooms, broccoli, onion, red bell pepper, and sriracha-spiked eggs with shredded cheese layered through. Add cooked sausage, bacon, or ham to make it higher in protein and more substantial for longer mornings.
Why you'll love this veggie breakfast casserole
14g protein per slice with eggs and cheese • 10 minutes of prep, 40 minutes in the oven • Makes 12 slices — meal preps the whole week • Colorful vegetables in every bite • Easy to add sausage, bacon, or ham for extra protein • Gluten free • Reheats in 90 seconds each morning
Ingredients
BASE CASSEROLE
10 large eggs
1 cup shredded cheese — cheddar, pepper jack, or Mexican blend
2-3 tablespoons sriracha — start with 2; it adds flavor warmth more than heat
1 teaspoon salt
1 teaspoon black pepper
1 tablespoon avocado oil
2 tablespoons minced garlic
VEGETABLES
10 oz sliced mushrooms
2 cups broccoli florets, roughly chopped
1/2 yellow or red onion, diced
2 red bell peppers, diced
OPTIONAL PROTEIN ADDITIONS (ADD ANY OR ALL, COOKED BEFORE ADDING TO CASSEROLE)
6-8 strips bacon, cooked and crumbled
1 lb breakfast sausage, cooked and crumbled — best choice for flavor and satiety
1 cup diced ham
Protein math with additions
Base recipe (eggs + cheese only): approximately 14g protein per slice.
With crumbled breakfast sausage added: approximately 20-22g protein per slice.
With crumbled bacon: approximately 16-17g protein per slice.
The sausage addition is the best choice if protein is the priority — it distributes evenly through the casserole and adds significant flavor.
The Layering Technique — Why It Matters
The layering approach makes this casserole different from just scrambling everything together. Here's how it works:
Egg mixture goes in first, then half the vegetables, then all the cheese, then the remaining half of the vegetables. The cheese layer in the middle creates two effects: it distributes melted cheese throughout the entire casserole rather than just on top, and it creates distinct visual layers when you cut slices — making each piece look and taste more intentional.
The peppers go in raw (off heat) while the other vegetables are still warm from sautéing — this gives them a slightly-softened-but-still-crisp texture rather than making them fully soft. If you prefer very soft peppers, add them to the pan with the mushrooms and onions instead.
Step-by-Step Instructions
Preheat. Oven to 375°F. Grease a 9x13 baking dish thoroughly — eggs stick aggressively to insufficiently greased pans.
Sauté the vegetables. Heat avocado oil in a medium skillet over medium heat. Add minced garlic, sliced mushrooms, and diced onion. Cook about 4 minutes until mushrooms have released their moisture and onions are softened. Turn off the heat and add the diced bell peppers and chopped broccoli — let them sit in the residual heat for 1-2 minutes to slightly soften without fully cooking.
Make the egg mixture. In a large bowl, whisk together all 10 eggs, sriracha, salt, and pepper until fully combined. If adding cooked crumbled meat (sausage, bacon, ham), add it here.
Assemble in layers. Pour the egg mixture into the greased baking dish. Add half the sautéed vegetables. Distribute all the shredded cheese evenly over the top. Add the remaining half of the vegetables over the cheese.
Bake. 35-40 minutes at 375°F until the center is fully set — a toothpick or knife inserted in the center should come out clean with no liquid egg. The top should be lightly golden.
Cool and slice. Let cool for 10 minutes before slicing into 12 even pieces. Slicing while very hot can cause the casserole to fall apart.
Meal Prep Guide
Cool completely before storing — warm casserole in a sealed container creates steam and makes the bottom wet
Store sliced pieces in airtight glass containers for up to 4 days
Reheat: microwave on 70% power for 60-90 seconds. Full power for more than 60 seconds can make the eggs rubbery.
Individual slice storage: wrap each slice in plastic wrap for the easiest grab-and-go
Freezer: freeze individual slices wrapped in plastic wrap then placed in a freezer bag. Up to 2 months. Thaw in the fridge overnight and reheat in the microwave.
Vegetable Swaps and Variations
Swap any bell pepper for zucchini — dice small so it cooks evenly
Add baby spinach or kale — stir into the egg mixture (it wilts during baking)
Sun-dried tomatoes instead of fresh — more concentrated flavor
Artichoke hearts (drained, chopped) — excellent in egg casseroles
Use pepper jack instead of cheddar — adds a mild heat throughout
Add everything bagel seasoning on top before baking for extra crunch
Frequently Asked Questions
How do I know when the casserole is done?
The center should be fully set with no jiggling liquid. Insert a knife or toothpick in the exact center — if it comes out clean, it's done. If wet egg clings to it, bake for 5 more minutes and check again. Start checking at 35 minutes.
Can I make this the night before and bake in the morning?
Yes — assemble the full casserole, cover tightly with plastic wrap, refrigerate overnight. In the morning, preheat the oven, add 5-8 minutes to the bake time since it's starting cold, and bake until set. This is actually the best approach if you want it fresh and hot on the morning you eat it.
Can I make it without cheese?
Yes — the casserole holds together with the eggs alone. Without cheese the protein per slice drops slightly and the flavor is lighter. Add an extra tablespoon of sriracha or fresh herbs (chives, dill, parsley) to compensate for the lost flavor.
More Low Carb Breakfast Recipes
Low Carb Veggie Breakfast Casserole
This easy low carb veggie breakfast casserole has 10 eggs, colorful vegetables, and melted cheese — baked in 40 minutes and meal preps all week. 14g protein per slice
Ingredients
Instructions
- Preheat. Oven to 375°F. Grease a 9x13 baking dish thoroughly — eggs stick aggressively to insufficiently greased pans.
- Sauté the vegetables. Heat avocado oil in a medium skillet over medium heat. Add minced garlic, sliced mushrooms, and diced onion. Cook about 4 minutes until mushrooms have released their moisture and onions are softened. Turn off the heat and add the diced bell peppers and chopped broccoli — let them sit in the residual heat for 1-2 minutes to slightly soften without fully cooking.
- Make the egg mixture. In a large bowl, whisk together all 10 eggs, sriracha, salt, and pepper until fully combined. If adding cooked crumbled meat (sausage, bacon, ham), add it here.
- Assemble in layers. Pour the egg mixture into the greased baking dish. Add half the sautéed vegetables. Distribute all the shredded cheese evenly over the top. Add the remaining half of the vegetables over the cheese.
- Bake. 35-40 minutes at 375°F until the center is fully set — a toothpick or knife inserted in the center should come out clean with no liquid egg. The top should be lightly golden.
- Cool and slice. Let cool for 10 minutes before slicing into 12 even pieces. Slicing while very hot can cause the casserole to fall apart.
Notes
- Cool completely before storing — warm casserole in a sealed container creates steam and makes the bottom wet
- Store sliced pieces in airtight glass containers for up to 4 days
- Reheat: microwave on 70% power for 60-90 seconds. Full power for more than 60 seconds can make the eggs rubbery
These high protein cheeseburger muffins have a hidden melted cheese center, only 0.5g net carbs each, and a homemade sugar-free burger sauce. Perfect meal prep lunch or easy dinner