Spinach-Artichoke Casserole

1/4 lb. butter
26 oz. frozen chopped spinach (16 oz. bag + 10 oz. box)
2 large cans artichoke hearts, drained
1 1/2 pints sour cream (reduced fat OK)
1 cup finely chopped onion
1 cup grated Parmesan cheese
salt and pepper

1. Preheat oven to 350ºF.
   
2. Place spinach in a microwave-safe dish and add 1/3 cup water. Cover the dish and microwave on High for 8 minutes. Drain the spinach.
3. While the spinach is cooking, sauté the onions in the butter until soft and translucent but not brown.
   
4. Dice artichokes or pulse them in a food processor for a few seconds, until they are roughly chopped.
5. Mix spinach, artichokes, onions, sour cream, and Parmesan cheese together. Add a few grinds of fresh pepper. Taste and add salt if necessary.
6. Place mixture in a 13"x9"x2" or a 10"x2" round casserole dish and spread evenly. Bake for 30 minutes.

Serve warm with assorted crackers.