Preheat your oven to 375 degrees Fahrenheit. Don’t forget to spray a large casserole dish with nonstick spray to ensure easy serving and less cleanup afterward. Now, slice your squash into 1/4-inch rounds. If you’ve got some larger squash, just slice them in half before cutting them into smaller pieces.
Heat your olive oil in a large non-stick frying pan over medium heat. Ah, that lovely scent of oil heating! Add in your sliced squash, minced garlic, and fresh thyme leaves, seasoning it all with salt to taste. Sauté gently, stirring until the squash begins to soften—but be careful not to overdo it. We want the squash to retain some of its delightful texture.
Once the squash has softened a bit, remove the pan from heat and introduce your sliced tomatoes. They’ll add a lovely juiciness to the dish.
Now grab a medium-sized bowl, and beat together your eggs, sour cream, crumbled feta cheese, grated Parmesan cheese, and lemon juice. Mix well until everything is combined and creamy.
Layer half of your sautéed squash mixture into the bottom of the prepared casserole dish. Sprinkle some salt and pepper over this layer, then pour half of the egg mixture on top. Repeat this layering with the remaining squash and egg mixture.
To finish, if you’re feeling indulgent, top the casserole with a bit of extra crumbled feta and grated Parmesan cheese for that extra touch of flavor!
Bake in the preheated oven for about 40-45 minutes. You’ll know it’s ready when the mixture is bubbling and slightly set. Serve it hot, and enjoy the creamy, cheesy goodness that is Parmesan Squash Casserole.