Vegetable Moussaka

1 4-lb eggplant, cut into 1/2-inch rounds
salt and pepper
1/4 cup plus 2 Tbs olive oil
1 large onion, chopped
1 10-oz container white mushrooms, sliced
1 cup diced zucchini
1 cup diced yellow squash
4 cloves garlic, minced
1 tsp dried oregano
1 28-oz can crushed tomatoes in puree
1/4 cup fresh parsley, chopped
1/2 cup, plus 4 Tbs, grated Parmesan
4 Tbs unsalted butter
5 Tbs all-purpose flour
3 cups milk
7 oz Greek yogurt
2 eggs, plus 2 egg yolks, lightly beaten

1) Preheat oven to 425F. Lay eggplant slices on paper towels and salt both sides; let stand for 30 minutes. Rinse and pat dry. Brush both sides with olive oil (1/4 cup total) and place on 2 baking sheets. Bake 20 minutes, turning slices and rotating pans halfway through. Remove eggplant from oven and let cool. Reduce oven temperature to 350F.
2) In a large skillet with a lid, heat remaining oil. Add onion, mushrooms, zucchini and squash, season with salt and pepper and cook, covered, over low heat until soft, about 10 minutes. Remove lid, turn heat to high and cook until liquid evaporates. Add garlic, oregano, tomatoes and puree and parsley and cook until sauce has thickened, about 10 minutes. Check seasoning and add more salt and pepper if necessary.
3) Mist a 13x9 inch baking dish with cooking spray. Cover bottom of dish with eggplant rounds, spoon half of vegetable sauce on top and sprinkle with 2 Tbs Parmesan. Repeat with remaining eggplant and sauce and 2 Tbs Parmesan, finishing with a top layer of eggplant.
4) Melt butter in pan and whisk in flour. Cook for 2 minutes. Whisk in milk and cook, stirring, until mixture comes to a boil. Reduce heat and simmer until sauce thickens, about 5 minutes. Add 1/2 cup Parmesan and yogurt and stir until smooth. Whisk in eggs and yolks.
5) Pour cheese sauce over eggplant. Place on a foil-lined baking sheet and bake until heated through and top is browned, about 70 minutes. Let rest for 20 minutes before slicing and serving.

Review: I replaced the eggplant with zucchini, doubled the yellow squash and omitted the 1 cup diced zucchini the recipe originally called for. I've never liked eggplant and have found that zucchini typically works well instead. It seemed to do the job for this dish! Because I used zucchini, I omitted the step of roasting, but I did sweat the zucchini. This dish made about 8 servings, so we had plenty of delicious food.