Hold up — before you think “vegan breakfast casserole” sounds boring, let me blow your mind. This is a fluffy, golden, absolutely satisfying morning masterpiece made with chunks of tangy sourdough bread soaked in a creamy cashew-based custard, loaded with sautéed veggies, and topped with melty plant-based cheese. It’s like French toast had a baby with a veggie scramble and decided to become the most epic brunch dish ever. Even your non-vegan friends are gonna be asking for seconds and the recipe. Plus, you make it the night before, so morning you just has to pop it in the oven and look like a breakfast genius.
Why You’ll Love This Recipe
Make it tonight, bake it tomorrow morning = hero status with zero morning effort.
Uses up day-old sourdough bread like a boss.
Packed with veggies but doesn’t taste like health food.
Feeds a crowd or gives you breakfast for days.
Dairy-free, egg-free, but still creamy and satisfying.
Perfect for holidays, brunches, or when you want to feel fancy on Sunday.
The Good Stuff You’ll Need
For the Bread Base:
8-10 cups day-old sourdough bread, cubed (about 1 large loaf)
2 tbsp olive oil for greasing
For the Veggie Mix:
2 tbsp olive oil
1 large onion, diced
2 bell peppers (any colors), diced
8 oz mushrooms, sliced
3 cups fresh spinach (or 1 cup frozen, thawed and drained)
3 cloves garlic, minced
1 tsp smoked paprika
1/2 tsp turmeric (for that golden color)
Salt and pepper to taste
For the Cashew Custard:
1 cup raw cashews, soaked for 4 hours (or quick-soaked in hot water for 30 minutes)
2 1/2 cups unsweetened plant milk (oat or soy work best)
1/4 cup nutritional yeast
2 tbsp ground flaxseed mixed with 6 tbsp water (let sit 10 minutes)
1 tbsp tahini or almond butter
2 tsp Dijon mustard
1 tsp garlic powder
1 tsp onion powder
3/4 tsp salt
1/2 tsp black pepper
1/4 tsp nutmeg
For the Topping:
1 1/2 cups shredded vegan cheese (cheddar or mozzarella style)
1/4 cup pumpkin seeds or chopped walnuts
Fresh chives or green onions for garnish
Optional Add-ins:
1/2 cup sun-dried tomatoes, chopped
1/4 cup fresh herbs (dill, parsley, or basil)
1/2 cup vegan sausage crumbles
Let’s Build This Beauty
Step 1: Prep Your Bread
Cut sourdough into 1-inch cubes. If it’s not day-old, toast lightly in a 300°F oven for 10 minutes.
Grease a 9×13 baking dish with olive oil.
Spread bread cubes evenly in the dish.
Step 2: Veggie Party Time
Heat olive oil in a large skillet over medium heat.
Sauté onion until translucent, about 5 minutes.
Add bell peppers and mushrooms. Cook until peppers are tender, about 8 minutes.
Add spinach, garlic, smoked paprika, and turmeric. Cook until spinach wilts.
Season with salt and pepper. Let cool slightly.
Step 3: Cashew Magic Custard
Drain soaked cashews and rinse well.
In a high-speed blender, combine cashews, plant milk, nutritional yeast, flax mixture, tahini, Dijon, and all seasonings.
Blend until completely smooth and creamy, about 2-3 minutes. It should be like thick cream.
Taste and adjust seasoning.
Step 4: Assembly Time
Scatter the cooked veggie mixture over the bread cubes.
Pour the cashew custard evenly over everything, making sure to get into all the corners.
Gently press down with a spatula to help bread absorb the liquid.
Cover tightly with foil and refrigerate overnight (or at least 4 hours).
Step 5: Morning Magic
Preheat oven to 375°F.
Remove casserole from fridge and let it come to room temp for about 20 minutes.
Sprinkle vegan cheese and nuts on top.
Bake covered for 30 minutes, then uncovered for 15-20 minutes until golden and set in the center.
Step 6: The Grand Finale
Let rest for 10 minutes before cutting (it’s molten hot!).
Garnish with fresh chives or green onions.
Cut into squares and watch people lose their minds over how good this is.
Serving Suggestions
Serve with fresh fruit and maybe some avocado slices for the full brunch experience.
A side of crispy hash browns never hurt anyone.
Pair with your favorite plant-based milk coffee drinks.
Switch It Up
Mediterranean Style: Add sun-dried tomatoes, olives, and fresh basil.
Mexican Fiesta: Use poblano peppers, add black beans, and top with salsa.
Mushroom Lover’s: Use a mix of wild mushrooms and add fresh thyme.
Sweet Version: Skip veggies, add berries and maple syrup to the custard.
Protein Boost: Add cooked white beans or chickpeas to the veggie mix.
Gluten-Free: Use gluten-free bread instead of sourdough.
Make-Ahead Tips
This literally needs to be made ahead — the overnight soak is what makes it amazing.
Can be assembled up to 2 days ahead. Just cover and keep chilled.
Individual portions can be cut and frozen for up to 2 months.
The veggie mixture can be prepped 3 days ahead.
Questions People Actually Ask
Q: Can I use regular bread instead of sourdough? A: Sure! Any crusty bread works, but sourdough adds amazing flavor.
Q: What if I don’t have cashews? A: Try silken tofu blended with plant milk, or use store-bought vegan cream.
Q: Can I skip the overnight step? A: You could, but it won’t have the same custardy texture. Give it at least 2 hours.
Q: How do I know when it’s done? A: It should be golden on top and set in the center when you shake the pan gently.
Q: Can I make this oil-free? A: Use water or vegetable broth to sauté the veggies instead of oil.
Q: What’s the best plant milk to use? A: Oat or soy milk work best because they’re creamier and help with binding.
Q: Can I add more vegetables? A: Absolutely! Just don’t go overboard or it might not set properly.
Print
Vegan Sourdough Breakfast Casserole
- Total Time: 1 hour 20 minutes
- Yield: 8–10 servings 1x
Description
Hold up — before you think “vegan breakfast casserole” sounds boring, let me blow your mind. This is a fluffy, golden, absolutely satisfying morning masterpiece made with chunks of tangy sourdough bread soaked in a creamy cashew-based custard, loaded with sautéed veggies, and topped with melty plant-based cheese. It’s like French toast had a baby with a veggie scramble and decided to become the most epic brunch dish ever. Even your non-vegan friends are gonna be asking for seconds and the recipe. Plus, you make it the night before, so morning you just has to pop it in the oven and look like a breakfast genius.
Ingredients
For the Bread Base:
8–10 cups day-old sourdough bread, cubed (about 1 large loaf)
2 tbsp olive oil for greasing
For the Veggie Mix:
2 tbsp olive oil
1 large onion, diced
2 bell peppers (any colors), diced
8 oz mushrooms, sliced
3 cups fresh spinach (or 1 cup frozen, thawed and drained)
3 cloves garlic, minced
1 tsp smoked paprika
1/2 tsp turmeric (for that golden color)
Salt and pepper to taste
For the Cashew Custard:
1 cup raw cashews, soaked for 4 hours (or quick-soaked in hot water for 30 minutes)
2 1/2 cups unsweetened plant milk (oat or soy work best)
1/4 cup nutritional yeast
2 tbsp ground flaxseed mixed with 6 tbsp water (let sit 10 minutes)
1 tbsp tahini or almond butter
2 tsp Dijon mustard
1 tsp garlic powder
1 tsp onion powder
3/4 tsp salt
1/2 tsp black pepper
1/4 tsp nutmeg
For the Topping:
1 1/2 cups shredded vegan cheese (cheddar or mozzarella style)
1/4 cup pumpkin seeds or chopped walnuts
Fresh chives or green onions for garnish
Optional Add-ins:
1/2 cup sun-dried tomatoes, chopped
1/4 cup fresh herbs (dill, parsley, or basil)
1/2 cup vegan sausage crumbles
Instructions
Cut sourdough into 1-inch cubes. If it’s not day-old, toast lightly in a 300°F oven for 10 minutes.
Grease a 9×13 baking dish with olive oil.
Spread bread cubes evenly in the dish.
Heat olive oil in a large skillet over medium heat.
Sauté onion until translucent, about 5 minutes.
Add bell peppers and mushrooms. Cook until peppers are tender, about 8 minutes.
Add spinach, garlic, smoked paprika, and turmeric. Cook until spinach wilts.
Season with salt and pepper. Let cool slightly.
Drain soaked cashews and rinse well.
In a high-speed blender, combine cashews, plant milk, nutritional yeast, flax mixture, tahini, Dijon, and all seasonings.
Blend until completely smooth and creamy, about 2-3 minutes. It should be like thick cream.
Taste and adjust seasoning.
Scatter the cooked veggie mixture over the bread cubes.
Pour the cashew custard evenly over everything, making sure to get into all the corners.
Gently press down with a spatula to help bread absorb the liquid.
Cover tightly with foil and refrigerate overnight (or at least 4 hours).
Preheat oven to 375°F.
Remove casserole from fridge and let it come to room temp for about 20 minutes.
Sprinkle vegan cheese and nuts on top.
Bake covered for 30 minutes, then uncovered for 15-20 minutes until golden and set in the center.
Let rest for 10 minutes before cutting (it’s molten hot!).
Garnish with fresh chives or green onions.
Cut into squares and watch people lose their minds over how good this is.
Notes
Serve with fresh fruit and maybe some avocado slices for the full brunch experience.
A side of crispy hash browns never hurt anyone.
Pair with your favorite plant-based milk coffee drinks.
- Prep Time: 30 minutes
- Cook Time: 50 minutes
Nutrition
- Calories: ~285 kcal
- Carbohydrates: ~28g
- Protein: ~12g
