Preheat oven to 350
Over medium heat, add squash, onion and olive oil to skillet and cook until veggies begin to lightly brown and soften, about 15 minutes. Remove from the skillet and let cool.
In a small bowl combine the softened butter and almond flour until it turns into a paste. Set aside.
In a separate bowl, mix together the cooked, cooled squash & onion mix, cheddar, mozzarella and parmesan cheeses, heavy cream, garlic powder, onion powder, salt, pepper and beaten egg.
Pour mixture into a 9×13 baking dish.
Drop small amounts of the almond flour & butter mixture on top of the squash & cheese mixture. Don’t worry about making this look nice and neat – just evenly drop over the casserole.
Bake for 40 minutes, until golden brown and bubbly.
After cooking, take a butter knife and “cut” the almond flour/butter topping to break up any clumps.
Sprinkle with paprika, green onions and serve!