Preheat the oven to 400 degrees.
Halve 2 medium zucchini lengthwise.
*With a small spoon, carefully scrape out the pulp, leaving a 3/8 inch thick shell. Steam the shells cut side down for 5 minutes. Coarsely chop the pulp. Heat in a small skillet until softened about 3 minutes:
2 Tbs olive oil or butter
3 Tbs. finely chopped onions or scallions
*Meanwhile, squeeze the moisture out of the chopped zucchini, then add it to the pan along with:
1 clove minced garlic
Cook for 2 minutes more. Turn into a bowl and combine with:
1 large egg. lightly beaten
1/2 cup Parmesan cheese
1/3 cup dry unseasoned bread crumbs
2 Tbs. chopped fresh parsley
1 tsp. marjoram, tarragon, basil or thyme
1/2 tsp lemon juice
Salt and ground black pepper to taste
*Spoon the filling into the zucchini shells and set them in a backing dish. Drizzle the tops with olive oil.
*Add water to come 1/8 inch up the sides of the shells. Bake until the zucchini is tender and the top is browned, about 30 minutes. Let cool for a few minutes before serving.