Making the Dough

1. Whisk together the flour and salt in a medium-sized bowl, toss your cubes of butter in the flour to coat them, flatten/crumble the butter between your fingers (you want a good mix of pea-sized pieces and large flat “shingles”). Make a small well in the middle, pour in half the ice water (1/4 cup), toss with the flour until evenly distributed. Add half the remaining water again (~1/8 cup), tossing to distribute. Then just keep gradually adding the water by the tablespoon until the dough holds together, but still crumbly (not wet).
2. Shape the dough into a disc, wrap tightly in plastic, and chill in the fridge for at least 1 hour (2 hours is ideal). Take out the dough, and on a lightly floured surface, roll it out into a large square (~10 inch). Fold in half one way, then fold in half the other (so it’s a quarter of the size). Roll it out into a square again and repeat the folds, using a small amount of flour if needed. Wrap tightly in plastic and chill in the fridge again for at least 30 minutes (up to 1 hour). This folding process creates layers and makes your dough much easier to work with.

Assembling/Baking the Apple Tart

1. On a lightly floured surface, roll out your dough until 1/4 inch thick (adding small bits of flour as needed to avoid sticking), and then trim into a large 10×14 inch rectangle (the size of a regular half sheet). Place on a parchment lined baking tray (half sheet or larger) in the fridge to keep cold while you prepare your apples. Preheat the oven to 400°F.
2. Peel and core your apples (if not done so already) and slice them as thinly as possible—I used a mandolin on the 1/8 inch setting, but you can also cut by hand with a sharp paring knife. Arrange your apples, slightly overlapping, in 3 or 4 rows and be sure to leave about an inch border around the outside (I used 3 apples and did 3 rows, which gave me a few slices left over to snack on—oh darn).
3. Sprinkle your granulated sugar overtop the apples, then evenly distribute your little cubes of butter around the top (see photos above, I cut my butter into tablespoon-sized pieces and then into quarters). Bake on the center rack of your oven at 400°F for 40-50 minutes or until desired browning on the crust, making sure to rotate the pan halfway through (see notes below on baking time/tips).
4. When there’s about 5 minutes left in the bake, melt your jam of choice in a small saucepan over medium heat with the water to thin it out. Once you take your tart out of the oven, immediately brush the warm jam overtop (the crust too). Let cool on the baking sheet for about 15 minutes before moving to a separate rack to cool even more.

Serve warm with some ice cream, dust with powered sugar (once completely cooled), or eat just as is like I did. Sometimes less is much, much more.

This is best enjoyed day-of, but will keep for a couple days stored in an airtight container at room temperature (the apples will loose a bit of their texture, so I highly recommend making and eating the day it’s made).