Preheat the oven to 375°
One a floured board, roll out the tart dough to an ⅛" thick rectangle that is a bit larger than about 18" x 6". Cut the sides to make them straight.
Move the dough onto a flat sheet pan by rolling the dough up around the rolling pin. brush water on the edges and turn in the sides to make a ½" rim. You can use a rimmed baking sheet lined with parchment paper so you can pick up the tart and move it.
With a fork, lightly press into the dough to seal the rim. If you have room in the refrigerator, place the dough there to chill while preparing the apples.
Peel, core, and quarter the apples, then cut into ⅛" thick slices. Put the slices in a large bowl and toss with the sugar, vanilla, and the melted butter.
Arrange two rows of apple slices on top of the dough. They should fit nicely side-by-side.
Place the tart in the oven and bake for 30 minutes, remove the baking sheet from the oven and sprinkle the chopped pecans on top and bake for an additional 15 minutes.
When done, let the tart cool slightly. Microwave the apricot jam for 30 seconds just to warm it up then brush on top of the tart.
Slide the tart onto a serving platter and cut into slices.
Cover any leftovers with plastic wrap and keep them for several days.