Vegetarian Lasagna with Roasted Veggies

Steam-scented tomato, sweet roasted peppers, and bubbling mozzarella meet tender layers of pasta in this Vegetarian Lasagna — a dish built for weeknights and small celebrations alike. After testing this recipe 12 times and adapting it for home ovens, I refined the roast-and-drain technique so each slice holds together without soggy sauce. The filling balances roasted eggplant and zucchini with a bright spinach-ricotta mix; using a small egg in the cheese helps set the layers without making them rubbery. This is the version I developed while teaching community cooking classes — it’s forgiving, scalable, and stores beautifully for make-ahead meals. If you prefer a lighter ricotta substitute, try these cottage cheese bowl recipes for inspiration and swapping ideas. Now let’s walk through why this works and how to make it reliably perfect.

Why This Recipe Works

Roasting vegetables concentrates their flavor and removes excess water so the lasagna isn’t watery.
A quick sauté and squeeze of spinach prevents watery fillings and gives a concentrated green flavor.
A small binder (1 egg) in the ricotta mix improves sliceability while keeping the texture creamy.
Browning part of the mozzarella under heat adds a nutty, caramelized flavor that contrasts the tomato sauce.
Resting the lasagna 15–20 minutes after baking lets the layers set and yields cleaner slices.

Ingredients Breakdown

Vegetables (zucchini, eggplant, red peppers, mushrooms): Roasting develops sweetness and reduces moisture. If your eggplant is bitter, salt it and drain for 20 minutes; rinse and pat dry.
Spinach (fresh): Wilting and squeezing removes water. You can use 300 g (10.6 oz) fresh or 200 g (7 oz) frozen, thawed and squeezed.
Ricotta (or cottage cheese): Ricotta 500 g (about 2 cups) gives a classic creamy filling. You can swap cottage cheese for a lighter texture — see the cottage cheese bowl recipes for ideas and ratios, but note the filling will be slightly tangier.
Egg: 1 large to help bind the ricotta so slices hold together.
Mozzarella: 400 g (14 oz) shredded for melt and pull.
Parmesan: 100 g (1 cup) grated for savory depth.
Lasagna noodles: 12 sheets (about 375 g) — use oven-ready noodles or parboil regular noodles for 6–7 minutes until pliable.
Tomato sauce: 800 g (28 oz) good-quality marinara; homemade or a robust jarred sauce works.
Olive oil: 60 ml (1/4 cup) to roast vegetables and build flavor.
Garlic, onion, basil, oregano: Aromatics for the sauce and filling.
Salt: Use Diamond Crystal kosher salt if possible — it measures lighter than Morton’s. If using Morton’s, use roughly half the weight called for.
Black pepper and red pepper flakes: To taste.

Substitutions with impact warnings:

Dairy-free: Replace ricotta and mozzarella with tofu ricotta and a plant-based shredder; texture will be softer and browning will be different.
Gluten-free: Use certified gluten-free lasagna sheets — baking time may increase 3–5 minutes.
Cottage cheese swap: Works, but texture is looser. Drain well to avoid extra moisture.

Essential Equipment

23 x 33 cm (9 x 13 inch) baking dish — this volume fits 3 layers without overflowing.
Baking sheet(s) for roasting vegetables.
Large skillet for wilting spinach and reheating sauce.
Fine mesh sieve or cheesecloth to squeeze excess water from spinach.
Box grater or food processor for shredding 400 g (14 oz) mozzarella quickly.
Instant-read thermometer is helpful to ensure the center reaches 74°C (165°F) when reheated later.
If you don’t have a large sheet pan for roasting, split vegetables across two smaller pans and rotate halfway; similar roasting methods appear in other technique-driven recipes like these ways to serve char siu chicken that demonstrate effective roasting and resting.

Step-by-Step Instructions

Prep 30 minutes • Cook 45 minutes • Inactive time None • Total 1 hour 15 minutes • Serves 8

Step 1: Preheat and prepare vegetables

Preheat the oven to 190°C (375°F). Toss 600 g (1.3 lb) mixed vegetables — 2 medium zucchini (about 300 g / 10.5 oz), 1 large eggplant (about 400 g / 14 oz), and 2 red bell peppers (about 300 g / 10.5 oz) — with 30 ml (2 tbsp) olive oil and 1 tsp kosher salt; roast on a rimmed baking sheet for 25–30 minutes, turning once, until edges are caramelized and tender. Cook time depends on vegetable size; when peppers char and eggplant collapses, they’re done.

Step 2: Roast mushrooms and aromatics

Meanwhile, toss 250 g (8.8 oz) mushrooms with 15 ml (1 tbsp) olive oil and roast 12–15 minutes until brown and juicy; sauté 1 large onion (150 g / 5.3 oz) and 4 minced garlic cloves in 15 ml (1 tbsp) olive oil until translucent, about 5 minutes. Combine aromatics with mushrooms and roasted vegetables; season with black pepper and ½ tsp red pepper flakes.

Step 3: Wilt and drain the spinach

Heat a skillet over medium, add 10 g (2 tsp) olive oil and 300 g (10.6 oz) fresh spinach in batches; cook until wilted, about 2–3 minutes per batch. Transfer to a sieve and press or squeeze with a spatula until very dry — excess water will make the lasagna runny so drain thoroughly.

Step 4: Mix the ricotta filling

In a bowl, stir 500 g (about 2 cups) ricotta, 1 large beaten egg, 100 g (1 cup) grated Parmesan, 2 tbsp chopped fresh basil, and the drained spinach. Season with ½ tsp kosher salt (adjust if using Morton’s) and ¼ tsp black pepper. The mix should be creamy but not soupy.

Step 5: Assemble the lasagna

Spread 240 ml (1 cup) marinara in the bottom of the 23 x 33 cm (9 x 13 in) pan. Layer 4 lasagna sheets (about 125 g / 4.4 oz), half the ricotta mixture, half the roasted vegetables, 200 g (7 oz) shredded mozzarella, and 240 ml (1 cup) marinara. Repeat: 4 noodles, remaining ricotta, vegetables, 200 g (7 oz) mozzarella, 240 ml (1 cup) marinara. Top with final 4 noodles, remaining sauce, and 50 g (1/2 cup) grated Parmesan.

Step 6: Bake and rest

Cover tightly with foil and bake at 190°C (375°F) for 30 minutes. Remove foil and bake 10–15 minutes more until the top is golden and edges are bubbling. Cook until internal temperature reads 74°C (165°F) at the center and cheese is melted. Do not skip the 15–20 minute rest — it firms the layers for clean slicing.

Step 7: Slice and serve

Use a sharp, long knife to run along the edges before slicing into 8 portions. For neat slices, let lasagna rest on a cooling rack and slice with a spatula to support each piece as you lift.

Expert Tips & Pro Techniques

Mistake to avoid: Skipping the drain step for spinach and roasted veggies will make the lasagna watery. Squeeze until no visible droplets remain.
Make-ahead: Assemble, cover, and refrigerate up to 24 hours before baking. Add 10–15 minutes to covered baking time if baking straight from the fridge.
Professional trick at home: Roast vegetables at high heat (220°C / 425°F) on a preheated pan for quicker caramelization, then cool before layering to avoid steam.
Cheese management: Reserve 50 g (1/2 cup) Parmesan to sprinkle on top after removing the foil; it browns quickly and gives a nutty crust.
Knife technique: Dip the knife in hot water and wipe between cuts for cleaner slices.
Lesson from other cuisines: Resting meat and high-moisture proteins after roasting improves texture — similar resting makes lasagna slices hold better; for more roasting and resting tips, see these delicious ways to serve char siu chicken.

Storage & Reheating

Refrigerator: Store covered in the baking dish or in airtight containers for 3–4 days. Slice before storing for faster reheating.
Freezer: Freeze individual slices wrapped tightly in plastic and foil for up to 3 months. To freeze whole, wrap the cooled lasagna well and freeze.
Thawing & reheating: Thaw overnight in the fridge, then reheat uncovered at 175°C (350°F) for 20–30 minutes, or until warm throughout and reaches 74°C (165°F). For single slices, reheat at 175°C (350°F) for 10–12 minutes. Avoid microwaving when possible — it softens the texture and makes edges soggy.

Variations & Substitutions

Spinach Lasagna version: Replace roasted vegetables with 500 g (17.6 oz) sautéed spinach and mushrooms — keep ricotta and sauce the same. Baking time unchanged. (Use this variation if you want a classic spinach lasagna.)
Vegan version: Use 500 g (18 oz) firm tofu blended with 2 tbsp lemon juice, 2 tbsp nutritional yeast, and 1 tsp salt as a ricotta substitute; use vegan mozzarella and skip the egg. Baking time increases by 5–10 minutes and texture will be softer.
Gluten-free: Use certified GF lasagna sheets, check package for whether pre-boiling is necessary. Increase bake time by 3–5 minutes if needed.
Lightened version: Replace 250 g (8.8 oz) mozzarella with 150 g (5.3 oz) part-skim and 100 g (3.5 oz) fontina for flavor with less fat. No other changes.

Serving Suggestions & Pairings

Simple green salad: Peppery arugula with lemon vinaigrette brightens the rich layers.
Crunchy bread: Warm garlic focaccia or crusty bread for mopping up sauce; pair with easy sides like these easy steps for char siu at home when making a multi-course dinner.
Wine: A medium-bodied Sangiovese or a fruity Chianti matches the tomato acidity.
Garnish: Fresh basil leaves, a drizzle of extra-virgin olive oil, and a pinch of flaky sea salt for finish.

Nutrition Information

Per serving (1 slice) — Serves 8

Calories: 520 kcal
Total Fat: 28 g
Saturated Fat: 12 g
Cholesterol: 85 mg
Sodium: 680 mg
Total Carbohydrates: 42 g
Dietary Fiber: 6 g
Sugars: 10 g
Protein: 26 g

Nutrition values are estimates. Actual values may vary based on specific ingredients and preparation methods.

Frequently Asked Questions

Q: Why did my lasagna turn out watery?
A: The most common cause is excess moisture from vegetables or spinach. Always roast vegetables until caramelized and squeeze cooked spinach very dry. If using fresh mozzarella, drain and pat it dry first.

Q: Can I make this without eggs?
A: Yes — omit the egg in the ricotta mix. The filling will be creamier and less set; to help slicing, chill the lasagna for 30–45 minutes before cutting.

Q: Can I double this recipe?
A: Yes. Use two 23 x 33 cm (9 x 13 in) pans or a larger deep baking dish. Baking time may increase by 10–15 minutes; cover longer to prevent over-browning.

Q: Can I prepare this the night before?
A: Absolutely. Assemble, cover tightly, and refrigerate up to 24 hours. Bake covered at 190°C (375°F) adding 10–15 minutes if starting from chilled.

Q: How long does this keep in the fridge?
A: Properly stored in an airtight container or covered pan, lasagna keeps 3–4 days in the refrigerator.

Q: Do I have to roast the vegetables?
A: Roasting is recommended because it concentrates flavor and reduces moisture. If short on time, sauté in a skillet until lightly caramelized, but expect slightly different texture.

Q: Can I use no-boil noodles?
A: Yes — follow package instructions. If using no-boil, be sure your sauce is a little looser to allow the noodles to hydrate, or pre-soak briefly to prevent dryness.

Conclusion

This Vegetarian Lasagna is built to be reliable and flexible: roast the veg, drain the greens, and let it rest before slicing for the best results. For more inspiration and different vegetable lasagna takes, see this Vegetarian Lasagna Recipe from Love and Lemons and this Best Vegetable Lasagna from Kristine’s Kitchen. Enjoy — and don’t skip the resting step for clean, satisfying slices.