Preheat the oven to 350°F. Spray an 11x7-inch baking dish with cooking spray and set aside.
For the filling, melt 3 Tablespoons salted butter in a large skillet over medium heat.
Once melted, add 2 pounds yellow squash, sliced about ¼-inch thick, 1 cup chopped sweet onion, 1 teaspoon kosher salt, 1/4 teaspoon black pepper, 1/4 teaspoon garlic powder and 1/4 teaspoon paprika. Stir to combine, so the squash is covered with the spices and butter.
Cook, stirring occasionally, until all of the squash begins to soften, 10 minutes.
Place a colander over a large bowl and add the cooked squash mixture. Allow to drain for 10 minutes.
In a large bowl, stir together 2 large eggs, 1/2 cup sour cream, 1/4 cup mayonnaise and 1 1/2 cups shredded sharp cheddar cheese.
Add the drained squash mixture to the egg mixture and stir to combine. Discard any liquid that drained off of the squash.
Place the mixture into the prepared baking dish.
For the topping, crush 1 sleeve Ritz crackers, crushed and add them to a medium-sized bowl (I like to keep some larger chunks of crackers and not completely crush them, this adds a nice texture to the topping).
Add 3 Tablespoons salted butter, melted and stir to combine.
Sprinkle the topping over the casserole. Bake for 15-20 minutes until golden brown on top and slightly bubbly along the edges.
Add dried parsley, for garnish and serve.
Video
Notes
Please refer to my FAQ’s and ingredient list above for other substitutions or for the answers to the most common questions.