3/4 cup grated Gruyere cheese, grated on a box grater
Preheat oven to 400°F degrees and place a rack in the middle. Rub a
9x9 gratin pan (or equivalent baking dish) with a bit of olive oil,
sprinkle with lemon zest, and set aside.
Place the zucchini slices into a colander placed over a sink, toss
with the sea salt and set aside for 10-15 minutes (to drain a bit)
and go on to prepare the oregano sauce and bread crumbs.
Make the sauce by pureeing the oregano, parsley, garlic, 1/4
teaspoon salt, red pepper flakes, and olive oil in a food processor
or using a hand blender. Set aside.
Make the breadcrumbs by melting the butter in a small saucepan over
medium heat. Cook for a few minutes until the butter is wonderfully
fragrant, and has turned brown. Wait two minutes, then stir the
breadcrumbs into the browned butter.
Transfer the squash to a large mixing bowl. Add the potatoes and
two-thirds of the oregano sauce. Toss until everything is well
coated. Add the cheese and half of the bread crumbs and toss again.
Taste one of the zucchini pieces and add more seasoning (salt or red
pepper) if needed.
Transfer the squash to the lemon-zested pan, top with the remaining
crumbs, and bake for somewhere between 40 and 50 minutes - it will
really depend on how thinly you sliced the squash and potatoes - and
how much moisture was still in them. You don't want the zucchini to
go to mush, but you need to be sure the potatoes are fully baked. If
the breadcrumbs start to get a little dark, take a fork and rake
them just a bit, that will uncover some of the blonder bits. Remove
from oven, and drizzle with the remaining oregano sauce.