Preheat your oven to 375°F (190°C). Lightly grease a baking dish with butter or oil and set aside.
Wash the zucchinis and slice them into 1/4-inch thick rounds. Toss the slices with a pinch of salt and let sit for 10 minutes to draw out excess moisture. Pat dry with paper towels to prevent sogginess.
While the zucchinis rest, grate the cheddar and mozzarella cheese. Prepare the breadcrumbs by toasting them in a pan with a tablespoon of melted butter until golden and fragrant, then set aside.
In a mixing bowl, whisk together the sour cream, beaten eggs, lemon juice, chopped herbs, and a pinch of salt and pepper. This will be your creamy filling layer.
Layer the zucchini slices evenly in the prepared baking dish. Spread a portion of the cheese mixture over the zucchini, then repeat the layers until all ingredients are used, finishing with a generous sprinkle of cheese on top.
Pour the remaining sour cream mixture evenly over the layered zucchini, ensuring it seeps into all corners. Sprinkle the toasted breadcrumbs and some extra cheese over the top for a crispy crust.
Bake in the oven uncovered for 35-40 minutes, until the top is golden brown and bubbling. The edges should be crisp, and the cheese melted and gooey.
Remove from the oven and let rest for 5-10 minutes. This helps the casserole set and makes slicing easier.
Slice and serve warm, garnished with extra herbs if desired. Enjoy the crispy topping with tender, cheesy zucchini layers.
