Did you know that a half-sheet pan and a jelly roll pan are NOT the same thing? They’re not. Definitely not. I learned this the hard way when I tried my first slab pie a couple weeks ago.
Since tis the season, I went with apples for the filling. I made the biggest hunk of pie crust I think ever in my life, chilled it, then proceeded to roll it out. I rolled, and I rolled, and then rolled some more, but I knew even before I transferred it to the half-sheet pan that it wasn’t going to fit. I tried stretching it to fit, but no matter what I did, I couldn’t get it to hang over the sides of the pan without ripping it.
And then I rolled out the second, smaller piece of dough, and no matter what I did, I couldn’t get it to meet the bottom crust. So the filling stuck out from the crusts about a quarter of an inch all around. Not great.
Thanks to Google, that all-knowing internet being I should have consulted in the first place, I learned that a jelly roll pan is a little smaller, and that’s what you’re supposed to use for slab pies. Amazon Prime got some prompt business from me, and we tried this again. And isn’t it so interesting, that when you use the right pan, slab pie is not difficult at all! So many facepalms…
Yes, please don’t repeat my dumb mistakes: make sure you are using the correct pan. You need a jelly roll pan, which will be labeled as such. They are 15×10 inches. If you don’t have one, they aren’t expensive and are totally worth it just to make this pie. It was hideously, fiendishly, unfairly delicious. Enjoy!
5 cups all purpose flour
1 tbs kosher salt
2 tsp granulated sugar
1 pound (4 sticks) cold unsalted butter, cut into small cubes
4 tsp cider vinegar
12 to 16 tbs ice water
7 medium to large Granny Smith apples, peeled, cored, sliced
1 1/4 cups granulated sugar
1/4 cup cornstarch
1 tsp ground cinnamon
1/2 tsp ground allspice
Juice of 1/2 a lemon (about 1 tablespoon)
1/4 tsp kosher salt
5 oz. toasted walnuts, rough chopped
1 egg, beaten
1/4 cup turbinado or other raw sugar
1/2 tsp ground cinnamon
First, make the CRUST: in a very large bowl, whisk together the flour, salt, and sugar. Add in the cubed butter and use a pastry cutter or 2 knives to cut the fat into the flour until the mixture is sandy and the butter is the size of small peas. Add the vinegar, then drizzle in the water. Use a rubber spatula to stir the dough together, using as few strokes as possible. When the dough has mostly come together, use your hands to knead the last straggly bits into the mound of dough. Divide the dough into two pieces with one slightly larger than the other. Think of a 60-40 split. Wrap both pieces of dough in plastic wrap and refrigerate at least one hour.
For the FILLING: preheat your oven to 375 degrees F.
On a lightly floured surface, roll out the larger piece of dough to an 18-by-13-inch rectangle. Fit into a 15-by-10-inch rimmed jelly roll baking sheet, pressing into corners (pastry will hang over sides). Chill while assembling filling.
In a large bowl, stir together the apples, granulated sugar, cornstarch, cinnamon, allspice, lemon juice, salt, and walnuts. Spread this mixture over the chilled pie shell. Chill again while you roll out the top crust.
On a lightly floured surface, roll out remaining piece of dough to a 16-by-11-inch rectangle; drape over the filling. Fold the edge of bottom dough over top dough. Crimp if desired. Prick the top dough all over with a fork. Brush entire surface of pie with the beaten egg (thinned with a little water if necessary). Mix the turbinado and cinnamon together and sprinkle evenly over the top crust.
Bake until the crust is golden brown and the filling is bubbling, 40 to 55 minutes. Transfer to a wire rack, and let pie cool until it is just warm to the touch, about 45 minutes. Serve warm or at room temperature, cut into 12 pieces. Slab pie is best eaten the same day it is baked, but it can be kept at room temperature, loosely covered with plastic wrap, for up to 2 days.