spinach artichoke casserole

ok, so....over these past 27 years that i have spent with my extended family of in-laws at thanksgiving, i have managed to morph their original creamed spinach recipe into one a little less slimy:

3 packages (10 oz) frozen chopped spinach, thawed/squeezed
1 onion, chopped
1 stick butter at room temperature
2 (6 oz) jars marinated artichoke hearts, drained
1 cup Parmesan cheese
8 ounce package cream cheese at room temperature

Satue onion in 2 tbsp butter until soft. Arrange at the bottom of a casserole dish (i use the clay rabbit dish with fitted lid) Chop artichoke hearts coarsely and arrange on top of onions. Spread thawed and squeezed spinach on top of artichokes- the more squeezed the better, as the casserole can get soupy if the spinach is too wet. Combine butter, Parmesan and cream cheese ; spread over spinach. Dish may be covered and chilled overnight at this point. About 45 minutes before the meal, remove from the refrigerator; allow to warm to room temperature for 15 minutes, then bake at 350 degrees for 30 minutes.