Preheat the oven to 400°F. Line a rimmed baking sheet with parchment paper (make sure it's rimmed, the juices will flow!).

Drizzle the honey onto the parchment in 6 evenly spaced "squiggles" creating 2 rows of 3. For each, draw a straight line with the honey that is about 2 inches long, then swirl the honey back and forth over the line in an "S" shape (see video). Set a pat of butter in the center of each. Your goal is to create a "grid" to lay the pastry on.

Sprinkle each pat of butter with a pinch each of brown sugar, cinnamon, and salt (exact measurements aren't necessary; just eyeball it).

Fan the apple slices over the pats of butter to create 3 long columns placed side by side. Start with the right or left side, running the apples evenly over the 3 pats of butter. Tuck the apples snugly against each other so no parchment peeks through (they will go up and over the pats of butter). Arrange the apples so they are fanning either directly towards or directly away from you.

Once you've finished the first column, complete the middle column, nestling the apples between the 2 columns of butter so they are directly on the parchment. For this column, lay the apples in short rows with the fans pointing left, then right (it will be slightly narrower than the other 2 columns)

Then, do the final column, arranging it over the remaining pats. You're aiming for a rectangle roughly 8x10 inches.

Unfold the puff pastry on a lightly floured work surface. Roll it into a rectangle that's about 2 inches longer than the apples on each side (mine was 10x13). Drape the pastry over the apples like a blanket. With the tines of a fork, press all the way around the edges of the pastry to create a border.

Brush the pastry lightly and evenly with the egg wash. Dab up any pools with a paper towel.

Bake for 30 minutes on the center rack, until the pastry is deeply golden and puffed.

Let rest for 5 to 10 minutes (some juices will have escaped and browned; simply scoop them away with a spoon and discard). Set a large cutting board over the pan and with one big, confident motion, flip it over. Lift away the pan and peel off the parchment. Dust with powdered sugar as desired and slice into squares.