Heat 2 tbsp olive oil in a large skillet over medium-high heat.

Add the sliced leek and mushrooms (use your favorite mix!). Sauté for 10 minutes, stirring occasionally, until the mushrooms release their moisture and turn golden.

Add the baby spinach, salt, dried garlic, and red pepper flakes. Stir well and cook for another 5 minutes until the spinach wilts. Set the filling aside.

Preheat your oven to 170°C (340°F).

Spread a thin layer of béchamel sauce (about ½ cup or 120 ml) on the bottom of a 9x13-inch (23x33 cm) baking dish.

Place a layer of lasagna noodles (dry or fresh) over the sauce, trimming if needed to fit.

Spread another thin layer of béchamel sauce over the noodles, followed by a layer of the mushroom-spinach filling.

Add another layer of lasagna noodles, more béchamel, and more mushroom filling.

Continue layering: noodles, béchamel, filling, until all the filling is used (usually 3-4 layers).

Finish with a final layer of noodles, pour over the remaining béchamel sauce, and generously sprinkle with shredded mozzarella and grated Parmesan.

For a decorative touch, scatter a few sautéed mushrooms on top.

Cover the dish with parchment paper, then aluminum foil (to prevent sticking).

Bake in the preheated oven at 170°C (340°F) for 30 minutes.

Remove the foil and parchment, increase the oven temperature to 200°C (390°F), and bake for an additional 10 minutes until the cheese is golden and bubbly.

Let the lasagna rest for 5-10 minutes before slicing. Serve hot and

enjoy!