Florentine Lasagna Recipe

Prepare aromatics

Heat a large skillet over medium heat. Add 2 tablespoons olive oil and 1 tablespoon butter. When butter foams, add finely chopped onion (about 1 cup) and a pinch of salt. Sauté 6–8 minutes until translucent and beginning to brown at the edges.

Cook mushrooms

Add sliced mushrooms (10 oz) to the pan in a single layer. Increase heat to medium-high and cook 6–8 minutes, stirring occasionally, until mushrooms release their liquid and it evaporates and the mushrooms brown. Season with 1/2 teaspoon of the salt and 1/2 teaspoon black pepper.

Add garlic and spinach

Stir in minced garlic (3 tsp) and cook 30–45 seconds until fragrant. Add packed baby spinach (10 oz) in batches if needed, stirring until wilted (2–4 minutes total). If excess liquid collects, cook an extra minute to evaporate. Taste and adjust seasoning with the remaining 1/2 teaspoon salt, 1/2 teaspoon black pepper, and grate in 1 teaspoon fresh nutmeg. Fold in toasted pine nuts (1 tbsp). Remove from heat and let cool slightly.

In a medium bowl combine 2 cups whole-milk ricotta, 3 oz finely grated parmesan, 1 egg, chopped parsley (2 tbsp), 1 tsp salt, and 1/2 tsp black pepper. Stir until smooth and homogenous. Once the spinach-mushroom mixture is cool (warm is OK), fold about half of it into the ricotta mixture to distribute vegetables through the filling; reserve the other half for layering.

Make roux

In a medium saucepan melt 4 tablespoons butter over medium heat. Add 1/4 cup all-purpose flour and whisk constantly for 1–2 minutes until the mixture becomes a pale blond paste and loses the raw flour smell.

Finish sauce

Slowly whisk in 3 cups warm whole milk a little at a time to avoid lumps. Bring to a gentle simmer over medium-low heat, continuing to whisk, until the sauce thickens enough to coat the back of a spoon (6–8 minutes). Remove from heat and stir in 1/4 tsp grated nutmeg, 1 tsp salt, 1/4 tsp white or black pepper, and 1/2 cup grated parmesan. Taste and adjust seasoning. Keep warm; if it skins, whisk briefly before using.

Preheat and prepare pan

Preheat oven to 375°F (190°C). Lightly oil a 9x13-inch baking dish with 1 teaspoon olive oil.

Layer 1

Spread a thin layer (about 3/4 cup) of béchamel on the bottom of the prepared dish to prevent sticking. Place 3 lasagna sheets in an even single layer over the sauce (overlap slightly if needed).

Layer 2 - ricotta & veggies

Spoon and spread half of the ricotta-vegetable mixture evenly over the noodles (about 1/2 of the mixture). Dollop and gently smooth about 1 cup béchamel on top of that layer. Sprinkle 2/3 cup shredded mozzarella evenly.

Layer 3 - repeat

Add a second layer of 3 lasagna sheets. Spread the reserved vegetable-ricotta mixture across that layer. Add another 1 cup béchamel and sprinkle another 2/3 cup mozzarella.

Top layer

Place the final 3 lasagna sheets. Spread the remaining béchamel evenly on top (about 1/2–3/4 cup) and sprinkle remaining mozzarella (about 2/3 cup) and 1/4 cup grated parmesan. Lightly cover the dish with aluminum foil (tent so cheese doesn't stick) for initial baking.

Bake

Bake covered at 375°F (190°C) for 25 minutes. Remove foil and bake an additional 10–15 minutes until bubbly and golden on top. If you like a more browned top, broil 1–2 minutes watching carefully to avoid burning.

Rest and serve

Let lasagna rest for 10–15 minutes after removing from the oven to set layers for cleaner slices. Garnish with additional chopped parsley or a sprinkle of grated parmesan and serve warm.