To clean the leeks, toss the sliced leeks into a big bowl of cold water and give them a good swish to rinse out any dirt. Scoop them out, repeating once more with fresh water if necessary. Drain in a colander, then gently pat dry with a clean towel.

Cook the pasta noodles:

• Heat oven to 425 ℉. Bring a large pot of water to a boil, season with salt (4 cups of water to 1 Tablespoon of salt) and lightly cook the lasagna sheets, until al dente, then drain. If the pasta is done before you’re ready to use it, lightly drizzle with olive oil so the sheets don’t stick together.

Saute zucchini and leeks

• Meanwhile melt 1 tablespoon of olive oil in a medium (10-inch) skillet over medium-high. Add the zucchini and leeks, garlic and cook. using tongs to toss and turn the Zucchini and leeks, until soft not mushy, 5 to 7 minutes. (Transfer to a large bowl.
At first the pan will be very full, but the vegetables will shrink quickly.

Make the béchamel

• Melt the 2 tablespoons butter in the skillet over medium-low, then whisk in the flour until smooth and begins to smell bisquit-y, about 1 minute. While whisking constantly, slowly pour in the milk in a thin stream and whisk until it’s incorporated. Whisk in salt, pepper, bay leaf, nutmeg, lemon zest until the sauce is smooth and slightly thickened, about 7 minutes. Turn off heat, squeeze juice of half a lemon. Taste and adjust as needed.

Layer the Lasagna

Using a loaf pan instead? You can easily make this lasagna in a standard loaf pan rather than two 16-ounce ramekins. You’ll need 6 lasagna sheets for two ramekins, but use only 5 sheets for loaf pan layering.
• When ready to assemble, remove the bay leaf from the white sauce. Then, place a couple tablespoons of bechamel on the bottom of each 16 ounce ramekin or loaf pan. Spread to cover the bottom. Lay one lasagna sheets over the sauce (it's okay if the noodles hang over the edge).

  For individual ramekins: Evenly divide spread a third of the zucchini mixture over the noodle in each ramekin. Now, spread ¼ cup bechamel then dot with a couple tablespoons of pesto in each ramekin. Repeat two more times: Noodle, zucchini mixture, bechamel sauce, pesto. Finish with the smoked gouda and mozzarella , a sprinkle of olive oil and a couple twists of freshly ground pepper.

  For a loaf pan: Layer a fourth of the zucchini mixture over the noodle. Now, spread heaping ⅛ cup bechamel then dot with a two tablespoons of pesto. Repeat four more times: Noodle, zucchini mixture, bechamel sauce, pesto. Using a total of 5 noodles. Finish with the smoked gouda and mozzarella , a sprinkle of olive oil and a couple twists of freshly ground pepper.
• Cover each ramekin or loaf pan with foil, place on baking sheet to catch any spills. Bake lasagna until it’s bubbling, about 15 minutes. Remove foil and continue baking until the edges are golden brown and the cheese has melted, 5-10 minutes.