Squash Casserole

Heat a large pot or Dutch oven over medium heat. Add olive oil and butter and swirl to melt and coat. Add the sliced squash, season generously with salt and pepper, and sautée for 10 minutes, stirring occasionally. Cover the pot with a lid and continue cooking for 15 minutes longer, stirring every few minutes, or until the squash is very tender. Stir in the minced garlic during the last 5 minutes of the cooking time. Add more salt and pepper until the squash is well-seasoned.

Adjust oven rack to the center position and preheat the oven to 350°F. Grease an 8-inch square casserole dish with softened butter or spray with nonstick cooking spray. Transfer the cooked squash to a large bowl and mash it with a potato masher to desired consistency. Mix in the sour cream to cool down the mixture (so that the egg doesn't scramble), then stir in the egg, cheddar, and 1/4 cup of the grated Parmesan until well-blended. Transfer mixture to the prepared baking dish and smooth the top.

Sprinkle the top of the squash mixture with the cracker crumbs and the remaining 1/4 cup Parmesan, then drizzle with the melted butter. Bake for 30 to 40 minutes or until bubbly and golden brown. Serve warm.