Preheat the oven to 350°F.
Melt a tablespoon of butter in a skillet.
Add the squash, bell pepper and onion, and cook 10 minutes stirring often.
Season with salt and black pepper and take off the heat.
Whisk the eggs with the sour cream, mayonnaise and cheese.
Stir the egg mixture into the skillet with the squash.
Spoon everything into a greased 8 or 9-inch square baking dish.
Mix the crushed Ritz crackers with a tablespoon of melted butter and sprinkle over the top.
Bake in the oven for half an hour or until the squash casserole is golden brown on top.