Squash casserole cooked in a cast iron skillet with a crunchy, buttery topping is a southern favorite side dish.
Heat oven to 375 degrees. Place cast iron skillet in oven to heat. When oven has come up to temp, take skillet out of oven and place 2 tablespoon of butter into pan. Place skillet back into oven for 3 minutes or until butter melts.
Carefully place sliced squash in buttered skillet. In a small bow or cup, mix together mayonnaise and milk. Pour over squash. Sprinkle on salt, pepper, garlic powder and 1 tablespoon of Parmesan cheese. Cover skillet with tin foil and place in oven. Cook for 20 minutes.
Melt butter in an oven proof dish. Add olive oil and Panko bread crumbs and mix. Set aside. Take skillet out of oven and remove foil. Sprinkle on buttered Panko crumbs and remaining Parmesan cheese. Place skillet back in oven, uncovered and cook an additional 10 minutes until topping is golden brown.
Remove skillet from oven and let cook for 5 minutes before serving.