One-Pan Smoky Veggie Lentil Lasagne

The first time I made this lasagne, my kitchen smelled like a cozy Italian restaurant on a rainy Tuesday afternoon. I had fallen in love with the idea of a one-pan lasagne after watching my friend Sarah somehow make dinner for eight people without dirtying every pot she owned. The smoky paprika hits your nose before you even take a bite, and something about that depth of flavor makes people think you spent all day cooking. My roommate actually asked if I had hidden a slow cooker somewhere.

I made this for my sister when she was recovering from surgery and she sent me a text at midnight saying she had eaten the leftovers cold standing in front of the fridge. There is something deeply comforting about the way the béchamel mingles with the smoky vegetable sauce as it bakes. The kitchen stays warm for ages after it comes out of the oven.

Ingredients

• Olive oil: A generous 2 tablespoons helps build the flavor base and keeps those veggies from sticking
• 1 large onion: Finely chopped so it melts into the sauce and becomes part of the overall richness
• 2 garlic cloves: Minced fresh because nothing wakes up a sauce quite like that first sizzle of garlic in hot oil
• 1 medium carrot: Diced small adds natural sweetness and depth that balances the smoky notes
• 1 red bell pepper: Diced into similar sized pieces as the carrot so everything cooks evenly
• 250 g mushrooms: Chopped into small pieces they shrink down and contribute this incredible savory backbone
• 2 medium courgettes: Dided small and they practically disappear into the sauce while adding moisture
• 1 tsp smoked paprika: This is the secret ingredient that makes the whole dish taste like it spent time over real flames
• 1 tsp dried oregano: Dried herbs work perfectly here since they will cook down with the sauce
• 1/2 tsp dried thyme: Earthy and warm it plays so nicely with the smokiness
• 1/2 tsp chili flakes: Optional but I love the gentle warmth that lingers after each bite
• 1 tbsp tomato paste: Concentrated tomato flavor that deepens the whole sauce dramatically
• 400 g chopped tomatoes: One can is exactly what you need for that perfect sauce consistency
• 1 tbsp soy sauce: The umami bomb that makes this taste so much more complex than it should
• 125 g dried red lentils: Rinse them well and they will cook down into the sauce creating this incredible creamy texture
• 500 ml vegetable stock: Good quality stock matters since it becomes the base of your sauce
• Salt and black pepper: Season generously at the end and taste before you declare it done
• 40 g unsalted butter: The foundation of a proper béchamel and worth every gram
• 40 g plain flour: This amount creates the perfect velvety consistency without becoming gluey
• 600 ml whole milk: Warm it slightly before adding and your sauce will come together much faster
• 1/4 tsp ground nutmeg: Just a pinch adds this subtle warmth that makes béchamel taste professionally made
• 60 g grated mature cheddar: Stir it into the sauce for that extra savory punch
• Salt and white pepper: White pepper keeps the sauce pristine looking while adding necessary seasoning
• 9 to 12 no-boil lasagne sheets: Have a few extra on hand in case you need to break pieces to fill gaps
• 50 g grated mozzarella: For that golden bubbly top that makes everyone immediately hungry
• Fresh basil leaves: Optional but they add this lovely fresh contrast right before serving

Instructions

Get your oven ready:

Preheat to 200°C (180°C fan) / 400°F / Gas 6 so you are not waiting around when the assembly is complete

Build your flavor foundation:

Heat the olive oil in a large ovenproof deep frying pan over medium heat and sauté the onion and garlic for 2 minutes until fragrant and softened

Add the veggie goodness:

Toss in the carrot red pepper mushrooms and courgettes and cook for 5 to 6 minutes until they have softened and the kitchen smells amazing

Wake up the spices:

Stir in the smoked paprika oregano thyme chili flakes and tomato paste and cook for 1 minute until the spices are fragrant and the tomato paste has darkened slightly

Create the smoky sauce:

Add the chopped tomatoes soy sauce red lentils and vegetable stock then bring to a simmer cover and cook for 15 to 20 minutes until the lentils are tender and the sauce has thickened beautifully

Season it perfectly:

Taste and add salt and pepper as needed remembering that the cheese will add more salt later so do not go too heavy handed

Make the silky béchamel:

Melt the butter in a medium saucepan over medium heat stir in the flour and cook for 1 minute then gradually whisk in the milk and cook stirring constantly for about 5 minutes until thickened

Finish the sauce:

Remove from heat and stir in the nutmeg cheese salt and white pepper until smooth and creamy

Start the layers:

Remove half the veggie bolognese from the pan and set aside then layer one third of the béchamel over the remaining sauce in the pan and top with lasagne sheets breaking them to fit

Build it up:

Spread half the reserved bolognese over the pasta pour over another third of béchamel and add another layer of lasagne sheets

Final assembly:

Finish with the remaining bolognese top with the final lasagne sheets and pour over the remaining béchamel then sprinkle with the grated mozzarella

Bake to perfection:

Cover loosely with foil and bake for 25 minutes then remove foil and bake for another 10 to 15 minutes until golden and bubbling all over

The hardest part:

Let it stand for 10 minutes before serving because this helps the layers set and makes serving so much easier

Save

This became my go to dish for new parents and people moving house because it travels well and tastes even better the next day. I once brought three pans to a friend who just had a baby and she texted me a week later asking for the recipe.

Making It Vegan

I have made this with dairy free butter oat milk and vegan cheese and honestly it was still incredible. The smoky paprika and soy sauce do so much heavy lifting that you barely notice the dairy is missing. My vegan friend actually said it was the best lasagne she had ever eaten.

The One Pan Magic

The genius of cooking the sauce right in the baking pan cannot be overstated. Every bit of flavor that would usually be left behind in a separate pot ends up in the final dish. Plus you look like a kitchen wizard serving lasagne from the same pan you cooked it in.

Perfect Pairings

A crisp green salad with an acidic vinaigrette cuts through the richness beautifully. Garlic bread is obviously never a bad idea but honestly this is substantial enough to stand on its own.

• Make a double batch and freeze one unbaked for those nights when cooking feels impossible
• The leftovers reheat surprisingly well in the microwave and the flavors get even better overnight
• If you have fresh basil growing somewhere tear it over the top right before serving for that hit of brightness

Save

There is something so satisfying about pulling this golden bubbling beauty out of the oven and watching everyone lean in a little closer at the table. Hope it brings as much comfort to your kitchen as it has to mine.

Recipe FAQs

→ Can I make this lasagne vegan?

Yes. Replace dairy butter with plant-based alternatives, use oat or soy milk for the béchamel, and choose vegan cheese varieties. The result remains creamy and satisfying.

→ What gives this dish its smoky flavor?

Smoked paprika is the key ingredient that provides the distinctive smoky taste. Don't omit it—it's essential to the dish's character. The soy sauce also adds depth and umami notes.

→ Do I need to cook the lasagne sheets first?

No. This method uses no-boil lasagne sheets that soften during baking. Breaking them to fit your pan is perfectly fine and ensures even coverage.

→ Can I prepare this in advance?

Absolutely. Assemble the entire dish up to 24 hours ahead, cover tightly, and refrigerate. Add 5-10 minutes to baking time if cooking from cold.

→ What works well as a side dish?

A crisp green salad with vinaigrette balances the richness. Garlic bread or roasted vegetables also complement the flavors beautifully.

→ How should I store leftovers?

Keep refrigerated in an airtight container for up to 3 days. Reheat portions in the microwave or cover with foil and warm in a 180°C oven.