The word casserole has been in French usage since at least 1583, meaning, "to cook in a casserole" (the dish/pot used for cooking it). In or before 1706 the word came unto English and used as a verb figuratively, to mean blending of some kind (typically having rice pounded and pressed similar to the pastry used for pies and used to encase fillings). Since at least 1930, a more open meaning appeared referring to the food prepared in the utensil itself.
In short: casserole - verb, noun ~ 1) to bake or cook food (in a casserole); 2) a baking dish of glass, pottery, etc., sometimes with a cover; 3) any food, usually a mixture, cooked in such a dish.
"Casserole....The word has a complicated history, starting with a classical Greek term for a cup (kuathos), progressing to a Latin word (cattia), which could mean both ladle and pan, then becoming an Old French word (casse...), which then became casserole...Historically, casserole cookery has been especially popular in rural homes, where a fire is in any case burning all day and every day...Although casserole is a western term, the use of cooking pots which would be called casseroles in Europe or Americas is almost universal in Asia."
---The Oxford Companion to Food, Alan Davidson [Oxford University Press:Oxford]
Now folks, it really don't matter where the word comes or how you use it. The most important thing is that we use it to make something good, something outstandingly tasty and something that at the end of the meal, when the casserole dish comes back empty, ya know you casseroled the best casserole your family could enjoy.
This is my take on a potato onion pie. Enjoy!
Potato Casserole Yum Yum
1 medium onion, halved and sliced thin
1/4 cup fully cooked real bacon pieces (Hormel Black Label)
6 garlic toes, minced
1 jalapeno, minced
1 cup grated mild cheddar cheese
1/3 cup grated Colby Monterey jack cheese
1/4 cup grated Parmesan cheese
2 pounds yellow potatoes, peeled and thinly sliced
salt to taste
1/2 cup heavy cream
Preheat oven to 350 degrees. Grease a 2 1/2-quart casserole with oil or cooking spray.
In a small bowl combine the bacon, garlic and jalapeno; put aside. In a medium bowl, combine the three cheeses; put aside.
Scatter 1/3 of the onions in the bottom of the casserole. Arrange half of the potatoes on top of the onions overlapping the slices. Lightly season with salt to taste. Sprinkle with 1/2 of the bacon mixture and top with 1/2 of the cheese mixture. Repeat layers with remaining onions, potatoes and bacon mixture. Pour the cream evenly over the top. Sprinkle with remaining cheese mixture. Cover with foil and bake for 1 hour.
Remove foil and continue baking for 30 minutes or until cheese turns golden. Remove and tent with the foil for about 5 minutes before serving.