Preheat oven to 350 degrees Fahrenheit.

Slice yellow squash and zucchini into bite-sized pieces.

Crush approximately 1.5 sleeves of Ritz crackers.

Spread the crushed crackers evenly across the bottom of a 9x13 inch glass baking dish.

In a mixing bowl, combine cream of mushroom soup, half and half, sour cream, cheddar cheese, onion flakes, salt, and pepper.

Add the sliced squash and zucchini to the soup mixture.

Stir gently to ensure the vegetables are evenly coated with the soup mixture.

Pour the vegetable and soup mixture into the prepared baking dish, on top of the crushed cracker base.

Bake in the preheated oven for 25-30 minutes, or until the vegetables are tender.

While the casserole is baking, crush the remaining Ritz crackers.

Melt the butter.

Combine the melted butter with the crushed remaining crackers.

Remove the casserole from the oven.

Sprinkle the buttered cracker topping evenly over the top of the casserole.

Return the casserole to the oven and bake for an additional 5-10 minutes, or until the cracker topping is golden brown.