This comforting zucchini casserole with buttery crackers and cheese is the perfect recipe for your bumper crop of zucchini. Fresh thyme is lightly floral while fresh ground pepper adds kick to this creamy summer casserole.
Preheat oven to 350°F. Lightly coat an 7-by-11-inch baking dish with cooking spray. Set aside.
Melt 1 tablespoon butter in a large nonstick skillet over medium-high heat. Add half of the zucchini and half of the onion; cook, stirring often, until the center of the zucchini is just tender and the liquid has evaporated, about 8 minutes. Transfer the mixture to a colander set over a bowl. Repeat the cooking process with the remaining zucchini and onion. Let the vegetables drain in the colander for 5 minutes.
Combine eggs, yogurt, mayonnaise, thyme, pepper and salt in a large bowl. Gently fold in the zucchini-onion mixture. Spoon evenly into the prepared baking dish. Sprinkle evenly with cheese.
Microwave the remaining 2 tablespoons butter in a medium microwaveable bowl on High until melted, about 25 seconds. Add crushed crackers to the melted butter and toss together until combined; sprinkle the topping evenly over the casserole. Bake until golden brown, about 20 minutes. Let stand for 5 minutes before serving.