Sheet Pan Tarte Tatin

Preparation

1. Make the caramel:

   1. Step 1

      Combine the sugar and ½ cup water in a medium saucepan. Gently stir with a heatproof spatula over medium-high heat to dissolve the sugar. When the mixture comes to a boil and the sugar is dissolved, forming a clear syrup, set the spatula aside (reserve it for a later step). Continue to cook, swirling the saucepan often and washing down the sides with a wet pastry brush to dissolve any stuck-on sugar crystals, until the syrup is thickened and the bubbles appear glassy and are slow to pop, about 5 minutes. 

   2. Step 2

      Lower the heat to medium and continue to cook, swirling gently and watching closely, until the syrup turns from golden to deep golden to amber and finally a deep amber (like a dark maple syrup). 

   3. Step 3

      Remove the saucepan from the heat and whisk in the butter and salt (watch out for steam) until the caramel is smooth and homogeneous. Pour the hot caramel across the bottom of a 10-by-15-inch jellyroll pan in an even layer. (It doesn’t need to cover every square inch.) Set the pan aside.

   4. Step 4

      Arrange a rack in the upper third of the oven and another rack in the center position. Heat the oven to 300 degrees. 

2. Prepare the apples:

   1. Step 5

      Peel the apples and cut in half through the stem. Use a paring knife to cut a notch out of the top and bottom ends of each half to remove any remaining peel and stem, then use a melon baller or round teaspoon measure to scoop out the cores and seeds. Place the apple halves on the jellyroll pan in an even layer, rounded sides down (no need to carefully arrange them at this point). In a glass or small measuring cup, combine the apple cider vinegar, vanilla and ¼ cup of water and pour around the apples into the bottom of the jellyroll pan. Cover tightly with foil, crimping around the sides.

   2. Step 6

      Place the jellyroll pan inside a sheet pan and transfer to the center rack of the oven. Bake until the apples have released some of their juices, the flesh is slightly translucent and a cake tester or paring knife slides through the halves with just a bit of resistance, 1 hour 15 minutes to 1 hour 30 minutes. Remove from the oven, uncover the apples, and let sit for a few minutes to cool. (Reserve the foil, as you may need it later.) Carefully transfer the apples to a large bowl or cutting board and set aside. 

   3. Step 7

      Heat the oven to 400 degrees. 

3. Reduce the caramel:

   1. Step 8

      Transfer the sheet pan with the uncovered jellyroll pan back to the oven, this time placing it on the top rack. After 10 minutes, slide the rack partially out of the oven (carefully) and stir the bubbling caramel mixture with the heatproof spatula to ensure any patches of solid caramel have melted again. Continue to bake, stirring every few minutes, until the caramel is thick and reduced, barely bubbling, and has returned to a deep, dark amber color, another 7 to 10 minutes. Remove the pan from the oven and set aside to cool. (Leave the oven on.)

4. Slice and arrange the apples:

   1. Step 9

      While the caramel is cooling, cut each of the parbaked apple halves crosswise into ¼-inch-thick slices. If you can, keep the halves intact while slicing, which will make arranging the apples faster and easier. When the caramel is cool (slightly warm is fine, just not hot), fan out the apple slices rounded-sides down and arrange across the jelly roll pan in tight, overlapping rows, leaving a ¼-inch space between the apples and the sides of the pan and tucking any excess apple slices into gaps. (You can even place extra slices flat on top of the fanned-out halves.) Set the pan aside. 

5. Roll out the pastry:

   1. Step 10

      Remove the thawed pastry from the refrigerator, unwrap and place on a lightly floured work surface. Roll out the pastry into a rectangle measuring a little longer and wider than the jellyroll pan, about 11 by 16 inches. If you’re using a box of puff pastry that contains 2 sheets, brush off any excess flour and lightly spray or brush one of the sheets with water, stack the second sheet over the first, aligning the corners, and roll out as above. Prick the pastry all over with a fork, roll it onto the rolling pin, then unroll it across the apples, doing your best to center it so there’s a small, even border on all four sides. Tuck the pastry inside the edges of the pan, then use a paring knife to pierce several more holes in the pastry, slicing down to the apples to encourage steam to escape during baking.

6. Bake and serve:

   1. Step 11

      Transfer the tart to the oven, still on the sheet pan to catch bubbling juices, and bake on the center rack until the pastry is puffed and deep golden brown and you see dark caramel bubbling up along the sides, 50 to 60 minutes. If the pastry is getting very brown before you see dark caramel, tent it with the reserved foil. Remove the tart from the oven and set aside to cool for 15 minutes, then invert it onto a cooling rack, using towels or oven mitts to protect hands from hot juices and lift away the jellyroll pan. 

   2. Step 12

      When ready to serve, slide the warm or room temperature tart onto a cutting board, cut into squares and serve with vanilla ice cream or whipped cream.