Apple, Mushroom and Sausage stuffed Acorn Squash

medium acorn squashes

butter or 1 TBSP olive oil

salt + pepper pork or chicken sausage, casings removed

large sweet onion

garlic, minced

large stalks of celery, diced

medium apple, peeled, cored and diced

cremini mushrooms, cleaned and sliced small

fresh thyme leaves

rosemary leaves, minced

fresh sage leaves, minced

large egg, beaten *see note

salt and pepper,

shredded white cheddar, mozzarella or gruyere cheese