Preheat oven to 400 F.
Melt unsalted butter (2 tablespoons) in a large skillet over medium heat.
Add chopped onions (1/2 cup) and saute for 8 minutes. Stir constantly.
Add sliced yellow squash (4 cups) and water (1/4 cup).
Cover and steam the veggies for about 5 minutes -- you'll know they're done once the squash is fork-tender.
Meanwhile, add the pork rinds (4 cups) to a large resealable bag.
Hit the bag with a rolling pin to crush the pork rinds, until they resemble small "bread crumbs".
Combine with shredded cheese (1 cup) and set aside.
In a medium bowl, whisk eggs (2), heavy cream (1/2 cup), xanthan gum (1/2 teaspoon),tabasco (1/2 teaspoon) *if using*, salt (1 teaspoon) and black pepper (1/2 teaspoon) together.
Stir in half the pork rind/cheese combo, along with the squash and onions.
Pour into a casserole dish (I used a 9" round casserole dish).
Top with remaining cheese and pork rinds.
Bake in preheated oven for 25 minutes, or until the top is golden brown.
Allow the casserole to cool before slicing, and enjoy!