Coarsely chop the spinach.
Melt the butter over medium heat & when bubbly add onion& garlic.
Saute for 2 minutes.
Add spinach, salt & pepper.
Cover & reduce heat to low steam for 3-4 minutes.
Put half of the cheese into an 8" greased casserole dish.
Add spinach, & nutmeg.
Cover with remaining cheese.
Bake in 350F for apprx 20 minutes or until cheese is browned.