How long do I need to cook fresh apples (sliced) in the oven (at 350 degrees) to get a good apple pie consistency?
Various factors influence the consistency of an apple when it bakes.
- Acidity. The more acidic the apple is, the better will the apple preserve its pectin and remain its crunch. Also any acidic fluids surrounding the apple will make an impact here.
- Thickness of the slices. Thin slices will make the apple heat up faster.
- The surrounding environments ability to transfer heat. If the apples are surrounded by a watery liquid heat will be transferred much more quickly to the apple than if it was surrounded by air. Other kinds of liquids will transfer heat quicker or slower.
So you see there are no hard and fast answers. But knowledge of these factors might help you build up experience to make a qualified guess in each case.
It really depends on a lot of things, as Jay said in his comment, not just the preparation of the pie (its depth, the amount of liquid/goop, whether it's covered) but also personal preferences, and the crispness of the apples you've decided to use.
Use a recipe as a guideline, and then check it periodically as it approaches the end time. If the apples aren't cooked enough for you and the crust is starting to brown, you can cover it loosely with foil to protect it. Remember what worked for the next time, and you should be set.