📖 Instructions

1. Prep Your Squash: First things first, wash your summer squash thoroughly. Using a sharp knife, trim off both ends. Now, slice the squash into quarter-inch thick rounds. If you have any really large squash, you might want to halve them lengthwise before slicing into half-moon shapes. Place these slices in a large colander.
2. Sweat the Squash (Crucial Step!): This is where we battle the dreaded watery casserole. Sprinkle about 1 teaspoon of salt evenly over the squash slices in the colander. Give them a gentle toss to distribute the salt. Let them sit there for about 15-20 minutes. You’ll see little beads of moisture forming—that’s exactly what we want! After resting, grab some paper towels and pat the squash slices *really* dry. Don't skip this; it makes a huge difference in the final texture. Seriously, it's worth the extra minute.
3. Sauté the Aromatics: While your squash is sweating it out, melt 2 tablespoons of unsalted butter in a large skillet or Dutch oven over medium heat. Add your chopped yellow onion and cook, stirring occasionally, until it's softened and translucent, about 5-7 minutes. Then, toss in the minced garlic and cook for just another minute until fragrant. Be careful not to burn the garlic!
4. Cook the Squash: Add your patted-dry squash slices to the skillet with the onions and garlic. Increase the heat slightly to medium-high. Cook, stirring frequently, for about 8-10 minutes, or until the squash is tender-crisp. You don't want it mushy yet, just softened enough. This step helps cook out even more moisture. Remove the skillet from the heat.
5. Make the Creamy Base: In a separate large mixing bowl, whisk together the cream of chicken soup (or mushroom, if you prefer a vegetarian option), sour cream, and mayonnaise until smooth. Stir in about three-quarters of your shredded cheddar cheese (reserve the rest for the topping) and season with salt and black pepper to taste. If you're feeling adventurous, a pinch of smoked paprika wouldn't hurt!
6. Combine Everything: Gently fold the cooked squash, onion, and garlic mixture into the creamy cheese mixture in the large bowl. Make sure everything is well combined and evenly coated.
7. Prepare the Baking Dish: Grease a 9x13 inch baking dish with a little butter or cooking spray. This prevents sticking and makes for easier cleanup.
8. Assemble the Casserole: Pour the squash mixture into the prepared baking dish and spread it out evenly with a spatula.
9. Make the Cracker Topping: In a medium bowl, crush your butter crackers until they are fine crumbs. You can do this by hand or by pulsing them briefly in a food processor. Melt the remaining 2 tablespoons of unsalted butter and pour it over the cracker crumbs. Toss until the crumbs are evenly coated. Stir in the remaining reserved shredded cheddar cheese.
10. Top and Bake: Sprinkle the buttery cracker-cheese mixture evenly over the top of the squash casserole. Pop the dish into your preheated oven at 375°F (190°C). Bake for 25-30 minutes, or until the casserole is hot and bubbly around the edges, and the topping is beautifully golden brown and crispy. If the topping starts to get too dark too quickly, you can loosely tent it with aluminum foil.
11. Rest and Serve: Remove the casserole from the oven and let it rest for 5-10 minutes before serving. This allows the casserole to set slightly, making it easier to scoop and preventing it from being too runny. Garnish with fresh parsley or chives, if desired. Serve warm and enjoy your little taste of summer!