Elderberry Apple Slab Pie
Makes 1 (10- by 15-inch) slab pie
2 ½ pounds tart apples (about 5 large), peeled and sliced
2 ½ pounds sweet apples (about 5 large), peeled and sliced
2 tablespoons juice and 1 teaspoon zest from 1 lemon
¾ cup plus 1 tablespoon sugar
2 tablespoons all-purpose flour
1 teaspoon cinnamon
¼ teaspoon ground nutmeg
¼ teaspoon ground allspice
¼ teaspoon salt
1 ½ recipes Maine Grains Double Crust Pie Dough, formed into 2 (4- by 6-inch) blocks
¼ cup dried elderberries
2 tablespoons cold butter, cut into ¼-inch pieces
1 large egg, beaten with 2 tablespoons warm water and a pinch of salt
In a large bowl, toss apples with lemon juice and zest, ¾ cups of sugar, flour, cinnamon, nutmeg, allspice, and salt, and toss until coated.
On a lightly floured surface, roll 1 block of dough into an 18- by 13-inch rectangle. Transfer dough to a 15- by 10- by 1-inch baking sheet and gently work it into the corners and along the edges of the pan. Trim any overhang to 3/4 inches. Turn apple mixture onto dough and spread it out into an even layer. Sprinkle elderberries evenly over the apples. Tuck pieces of butter into the apples all around the pie.
Roll second block of dough into a 16- by 11-inch rectangle. If desired, use a small cookie cutter to make a series of shapes in the dough. Transfer dough (leaving the cutouts on the counter) to drape over filling. Fold the bottom crust’s overhang up over edges of the top dough. Crimp edges. Place cutouts around surface of pie. If you have not made any cutouts, use a paring knife to cut 9 small slits over the surface. Refrigerate at least 30 minutes.
Position rack in the lower half of the oven and preheat oven to 375°F.
Brush beaten egg mixture over top of crust and sprinkle evenly with the remaining tablespoon of sugar.
Place pie in oven. Bake until top crust is golden, 20–25 minutes. Rotate pie and reduce oven temperature to 375°F. Bake until juices bubble and crust is deep golden brown, 30–35 minutes. Transfer pie to wire rack; cool to room temperature, about 2 hours.