Preheat oven to 350° F. Wash and slice squash and zucchini thinly and dice onion. Add butter to large fry pan and sauté onion, garlic and mushrooms until soft and fragrant.
Add zucchini and squash to pan and fry until soft stirring often. In a separate bowl, combine all ingredients except cheeses. Add squash mixture and stir until fully incorporated.
Add all parmesan cheese and 1/2 Colby-Jack cheese to mixing bowl. Stir gently until incorporated.
Pour mixture into baking dish or cast iron skillet, sprinkle Italian seasoning evenly over the top (if using) and cover with foil. Bake at 350° F for 15-20 minutes or until cheese is melted fully. Remove foil and broil on low for 3 minutes to brown cheese slightly making sure it does not burn. Remove from oven and allow it to rest for 8-10 minutes.
Cheesy Squash Casserole https://sixdollarfamily.com/the-best-cheesy-squash-casserole-recipe September 27, 2020