Veggie Pesto & Spinach Lasagna

This Veggie Pesto & Spinach Lasagna is the kind of comforting, verdant bake you want on repeat. Think layers of tender lasagna sheets, a creamy, glossy béchamel dotted with fragrant basil pesto, and a generous bed of cooked spinach softened with sweet onion. It’s rich without feeling heavy, bright with pesto, and utterly satisfying on a weeknight or for guests. The recipe makes a generous family-size dish and keeps well for quick reheats. Follow the clear step-by-step directions below to build a beautiful, bubbling lasagna that slices cleanly and tastes like the kind of home cooking you’ll want to serve again and again.

Why you’ll love this lasagna

This Veggie Pesto & Spinach Lasagna brings together comforting dairy elements and the fresh lift of basil pesto. The sauce is a smooth white sauce that carries the pesto evenly through every bite, while the spinach and onion add texture, color, and gentle sweetness. It’s a great vegetarian center stage for a meal—simple to assemble, impressive on the plate, and flexible for serving. The ingredients are supermarket staples, and the method is forgiving, making it ideal whether you’re a confident cook or trying something new.

Ingredients

• 1 large onion, finely chopped
• 600 g spinach, coarsely chopped
• 100 g butter
• 100 g flour
• 1 l whole milk
• 300 g basil pesto
• 100 g parmesan + extra for sprinkling
• 1 packet of lasagna sheets
• salt
• pepper
• olive oil

Prep and timing

Hands-on time: about 30–40 minutes. Oven time: 25–35 minutes. Total: about 1 hour to 1 hour 15 minutes depending on your oven and whether you parboil lasagna sheets. Prepare a 9×13-inch (or similarly sized) baking dish, preheat the oven to 180°C (350°F), and have a wooden spoon, saucepan, and a shallow frying pan ready.

Step-by-step directions

The directions below follow a clear sequence so you can cook efficiently: soften the onion, wilt the spinach, make the béchamel, assemble the layers, and bake. Read through once before starting so everything flows smoothly.

1. Cook the onion

1. Heat a drizzle of olive oil in a wide frying pan over medium heat.
2. Add the finely chopped onion and a pinch of salt. Cook, stirring occasionally, until the onion is soft and translucent, about 6–8 minutes. Do not brown; you want a sweet, tender base for the spinach.

2. Wilt the spinach

1. Increase the heat slightly and add the coarsely chopped spinach to the pan with the softened onion. You may need to add the spinach in batches; it will quickly collapse.
2. Cook the spinach with the onion, stirring until fully wilted and any excess liquid has mostly evaporated, about 4–6 minutes. Season with a pinch of salt and a little black pepper to taste. Remove from heat and set aside.

3. Make the béchamel (white sauce)

1. In a medium saucepan, melt 100 g butter over medium heat until just foaming but not browned.
2. Add 100 g flour to the melted butter and whisk immediately to form a smooth roux. Cook the roux for about 1–2 minutes, whisking constantly, so the raw flour taste cooks out. Keep the color pale; we want a creamy sauce rather than a nutty brown flavor.
3. Slowly add 1 l whole milk in a steady stream while whisking continuously to prevent lumps. Continue whisking until the sauce is smooth and begins to thicken, about 6–8 minutes.
4. Once the béchamel has thickened to a consistency that coats the back of a spoon, remove from heat. Stir in 300 g basil pesto and 100 g parmesan until fully incorporated and smooth. Taste and season with salt and pepper as needed. The result should be a creamy, slightly green, pesto-flavored white sauce.

4. Assemble the lasagna

1. Prepare your baking dish by lightly drizzling a little olive oil across the bottom or using a thin layer of the béchamel to prevent sticking.
2. Spread a thin, even layer of the pesto-béchamel on the base of the dish—about one-quarter to one-third cup—to create a moisture barrier.
3. Place a single layer of lasagna sheets on top of the sauce. If your lasagna sheets require pre-cooking according to package instructions, follow those directions before layering. If they are oven-ready, you can layer them dry.
4. On the first sheet layer, distribute roughly half of the cooked spinach and onion mixture in an even layer. Spoon over a generous ladle of the pesto-béchamel so the spinach is well coated and moist. Sprinkle a light handful of the 100 g parmesan across the layer.
5. Add another layer of lasagna sheets and repeat with the remaining spinach mixture, more sauce, and another sprinkle of parmesan.
6. Finish with a final layer of lasagna sheets and pour the remaining pesto-béchamel evenly over the top. Use a spatula to spread the sauce so it reaches the edges. Sprinkle extra parmesan across the surface for a golden, savory crust when baked.

5. Bake

1. Cover the baking dish loosely with foil and place it in the preheated oven at 180°C (350°F).
2. Bake covered for 20 minutes to heat through and allow the flavors to settle.
3. Remove the foil and continue baking for another 10–15 minutes, or until the top is bubbling and the cheese on top is golden and slightly crisped. If you prefer a very browned top, transfer the lasagna under a hot grill for 1–2 minutes—watch carefully to avoid burning.
4. Once baked, remove the dish from the oven and let it rest for 10–15 minutes before cutting. Resting helps the lasagna set so you get clean slices.

Troubleshooting & tips

• If your béchamel seems too thick before assembly, whisk in a splash of milk to loosen it—better to have a spoonable consistency than one that is stiff.
• For easier slicing, let the lasagna cool for the full resting time; it will hold together much better.
• If using oven-ready lasagna sheets, ensure your béchamel is slightly more fluid during assembly so the sheets can hydrate while baking.
• You can add extra texture with a layer of roasted sliced mushrooms or thinly sliced zucchini between the spinach and lasagna sheets for more vegetable variety without changing the recipe’s structure.

Serving suggestions

Serve slices of Veggie Pesto & Spinach Lasagna with a crisp green salad dressed simply with lemon and olive oil to cut through the richness. A side of crusty bread or garlic-rubbed toast makes this a full, comforting meal. Leftovers reheat well in the oven at 160°C (320°F) for 15–20 minutes or in a microwave for a quick lunch.

Storage

Store leftovers covered in the refrigerator for up to 4 days. To freeze, cool completely, then wrap the whole dish tightly in foil and freeze for up to 2 months. Thaw overnight in the refrigerator before reheating in the oven until piping hot.

Ingredient notes and small swaps

• Spinach: Fresh spinach is used here; if you prefer frozen, thaw and squeeze out excess water before sautéing with the onion. Keep the 600 g quantity for the same yield.
• Basil pesto: Use a quality store-bought pesto or homemade if you prefer. The pesto gives the béchamel its defining flavor—300 g is a generous amount so the herbaceous note carries through the dish.
• Parmesan: Use a good-quality hard grating cheese labeled as a suitable alternative if needed; measure 100 g into the béchamel and reserve extra for sprinkling.
• Lasagna sheets: If your lasagna sheets require pre-boiling, follow package instructions to cook them al dente before layering. If they are labeled oven-ready, layer them dry.

Final thoughts

This Veggie Pesto & Spinach Lasagna is straightforward yet indulgent—perfect for a cozy family dinner or a potluck where you want a vegetarian centerpiece. The pesto-infused béchamel is the star, coating every layer with herbal, creamy flavor while the spinach and onion offer balance and body. The assembly is forgiving, and the results are reliably delightful: creamy, green, and deeply satisfying. Make it your own by adding roasted vegetables or extra cheese on top, but rest assured, even with the basic ingredients and straightforward method, this lasagna will impress.

Enjoy baking, savor each slice, and don’t forget to let it rest before serving so every piece looks as good as it tastes.