Preheat your oven to 375°F (190°C) and grease a 9x13 inch baking dish.

In a large pot, bring water to a rolling boil and add the sliced yellow squash. Boil for 8-10 minutes until tender, then drain well in a colander.

In a mixing bowl, combine the drained squash with melted butter, sour cream, shredded cheddar cheese, chopped onion, salt, and pepper. Mix until well-combined.

Pour the squash mixture into the greased baking dish and spread evenly.

Sprinkle the crushed crackers over the top of the mixture and press lightly.

Bake for 25-30 minutes until bubbly and golden brown.

Remove from the oven and let sit for 5-10 minutes before serving.