Spinach & Mushroom Lasagna

A British-style vegetarian lasagna that swaps tomato sauce for a pureed mushroom gravy, giving the dish a deep umami backbone that even committed carnivores tend to ask about. The mushroom sauce is unusual but works because the puree clings to every noodle without the bright acid of tomato fighting the ricotta.

The spinach gets cooked dry in its own water (no extra liquid added), which concentrates the flavor and avoids the watery filling that ruins most vegetable lasagnas. Adding a touch of marjoram and folding the ricotta in once the spinach has cooled is the move that gives the filling its mossy green color and herbaceous edge.

A splash of soy sauce in the mushroom sauce is the trick that pushes the umami over the top. It reads as savory depth, not Asian flavor, and turns standard sauteed mushrooms into something that can stand against ground meat ragu.

Chef Tips

• Squeeze the cooked spinach hard in a clean kitchen towel before chopping. Wet spinach waters down the ricotta and the lasagna leaks once sliced.
• Cover the pot tightly when cooking the mushrooms with stock. The trapped steam concentrates the juice instead of letting it evaporate.
• Puree the mushroom sauce briefly, just a few pulses. Over-blending turns it gluey instead of velvety.
• Let the lasagna rest 10 minutes after baking before slicing. The layers set and each portion holds its shape on the plate.

Variations

• Use a mix of cremini, shiitake, and oyster mushrooms for more complex flavor.
• Substitute butter for margarine throughout if dairy isn’t a concern.
• Add a thin layer of mozzarella between the pasta sheets for additional cheesy pull and a more familiar lasagna profile.