Preheat your oven to 400 degrees (any other temperature should work if you’re baking a pie at the same time).
On a piece of parchment or wax paper, roll out the crust into a rough circle until very thin, about 1/8-inch. Transfer the crust to a baking sheet and arrange the apple slices in an overlapping circle on top of the crust, leaving a ¾-inch border of plain crust all around. Fold the crust over the apples to form the galette.
Brush the crust with a little milk and sprinkle with sugar—maybe ½ a teaspoon. Bake for 25-30 minutes, or until the apples start to look dry and browned around the edges.
While the crust is baking, make the date caramel. Check on the galette. If you poke it, the apples should feel soft and dry to the touch. Remove the baking sheet and brush the apples with the caramel. Return to the oven and bake for another 5-10 minutes.
If you’re only making one tart, you will have leftover caramel (eat it in parfaits, spread it on bread, dump it into whatever other pie you’re making—I’m sure you’ll find a use for it).