Preheat your oven to a cozy 400°F (200°C).
Place the chopped yellow squash into a skillet with a couple of tablespoons of water over medium-high heat. Let it cook gently for about 5 minutes until it's just tender-crisp.
Carefully drain any remaining water from the squash. Add the chopped green onion to the skillet and sauté for just one minute until fragrant. Season with salt and pepper to your personal taste.
Transfer this flavorful squash mixture into a well-greased 9x9 inch baking dish, spreading it evenly across the bottom.
In a separate bowl, whisk together the egg and 1/2 cup of heavy whipping cream until they're nicely combined. Pour this creamy mixture evenly over the squash in the baking dish.
Sprinkle the 1 cup of shredded cheddar cheese generously over the squash and cream layer.
For that amazing crunch, crush about 2 ounces of pork rinds to create 1/2 cup of crumbs. (A food processor or a Ziploc bag with a rolling pin works great!)
In a small bowl, combine the 1/4 cup of grated Parmesan cheese with your pork rind crumbs.
Stir the 2 tablespoons of melted butter into the pork rind and Parmesan mixture until everything is well coated.
Evenly sprinkle this delicious, buttery crumb mixture over the top of your squash casserole. Bake in your preheated oven for 20 minutes, or until the topping is golden brown and bubbling beautifully.
Once out of the oven, garnish with a sprinkle of freshly chopped green onions for a burst of color and flavor. Let it cool slightly before serving and savoring this wholesome dish!