All fruits and vegetables, apples are held together by pectin, a carbohydrate glue that acts as the mortar between cells. Break down this pectin by heating it to around 185°F (85°C) and your apples will turn mushy. However, as the magazine explains, natural enzymes in the apple can convert that pectin to a more heat-stable form if the apple is held for prolonged periods of time at temperatures close to (but not over) 160°F, or 71°C.
To confirm this, I cooked two miniature apple crisps by tossing apple slices with cinnamon, sugar, cornstarch, and a little lemon juice. Then I took half of the apple slices and cooked them to 160°F (71°C), holding them there for 15 minutes before letting them cool to room temperature. I then baked both batches of apple in identical containers topped with a simple oat, butter, and brown sugar crisp topping.
As you can plainly see, the par-cooked apples stay fully intact, separating into individual slices. They have a tender bite but aren’t mushy. The raw apples, on the other hand, get the applesauce-like texture.
There are a number of ways you can get your apples to 160°F and activate those enzymes. The microwave and the stovetop both work well, though both require some temperature management and a careful eye on the thermometer (you don’t want to overheat the apples or the enzyme gets deactivated and you end up with applesauce). The key is to take it slow, and stir constantly.
Sous Vide Supremacy
Of course, if you have a sous vide cooker (like the Anova Precision Cooker), this whole temperature game becomes much easier. By bagging your seasoned apple slices and placing them in a 160°F (71°C) water bath, you can very easily set their pectin before finishing them on a stovetop, just like with the Dutch oven method.
I tried holding batches of apples in my sous-vide setup for times ranging from 15 minutes up to six hours and found that the optimal balance was around 1 hour. Not too long to make this an all-day project, but long enough to give you apples that hold their shape extremely well as they bake. (Besides, after an hour in the sous-vide bath, you get increasingly diminishing returns with longer sous-vide times.) Compared to the all-stovetop or microwave method, sous-vide is easier (no fiddling around with heat levels), way more foolproof, and produces superior results.
Once you’ve got that filling par-cooked, the rest is, well, pie. Start by making a good pie dough and line a pie plate with one of the disks. Add the (completely cool!) apple filling, and top it with a second disk.
Next, trim both edges together until they overhang the pie plate by about half an inch. Then you can tuck them underneath until they’re flush with the edge of the pie plate. Flute the edges using your thumb and forefinger from one hand and the forefinger from the other. I find that lightly flouring your fingers for this step can help you work faster and prevent you from accidentally sticking yourself to the dough.
Finish off your pie by brushing it with an egg white (this helps it brown and gives it a nice glossy appearance), sprinkling it with sugar (to give it crunch and texture), and cutting a few vent holes (them apples gotta breathe).
If you’ve taken a long time to assemble the pie, your home is particularly warm, or you’re just the paranoid type, at this stage you can stick your pie back in the fridge for half an hour (or into the freezer for 15 minutes) to ensure that the pastry is nice and firm. The goal is to cook it hot right at the beginning so that the outer layers of pastry firm up and give the crust structure before the cold interior layers start to soften so much that the pie crust slouches or melts. I start my crust at 425°F (220°C) for about 20 minutes, then lower the oven to 375°F (190°C) and continue baking it until it looks like this:
Looks almost good enough to eat, doesn’t it? But don’t! Not yet, at least. LEFTOVER apple pie is good warmed up. It’s settled enough and lost enough moisture that even warm it’ll retain its gooey texture and hold its shape. But fresh-from-the-oven apple pie still needs to cool before slicing, lest all that work we put into those tender-yet-firm apple slices and the gooey reduced liquid binding them together goes to waste in a puddle at the bottom of the pie plate.
Let your pie cool fully to room temperature before slicing (I make mine the day before and let it rest on the counter overnight before serving), and then slice it with a sharp knife.
Repeat: LET IT COOL.
This is what you’re rewarded with.