Step 1

Toss peaches, ½ cup sugar, lemon zest and juice, and salt in medium bowl. Let stand at room temperature for at least 30 minutes or up to 1 hour. Combine pectin, cinnamon, nutmeg, and 2 tablespoons sugar in small bowl and set aside.

Step 2

Remove dough from refrigerator. Before rolling out dough, let it sit on counter to soften slightly, about 10 minutes. Roll 1 disk of dough into 12-inch circle on lightly floured counter. Transfer to parchment paper–lined baking sheet. With pizza wheel, fluted pastry wheel, or paring knife, cut round into ten 1¼-inch-wide strips. Freeze strips on sheet until firm, about 30 minutes.

Step 3

Adjust oven rack to lowest position and heat oven to 425 degrees. Roll other disk of dough into 12-inch circle on lightly floured counter. Loosely roll dough around rolling pin and gently unroll it onto 9-inch pie plate, letting excess dough hang over edge. Ease dough into plate by gently lifting edge of dough with your hand while pressing into plate bottom with your other hand. Leave any dough that overhangs plate in place. Wrap dough-lined pie plate loosely in plastic wrap and refrigerate until dough is firm, about 30 minutes.

Step 4

Meanwhile, transfer 1 cup peach mixture to small bowl and mash with fork until coarse paste forms. Drain remaining peach mixture through colander set in large bowl. Transfer peach juice to liquid measuring cup (you should have about ½ cup liquid; if liquid measures more than ½ cup, discard remainder). Return peach pieces to bowl and toss with cornstarch. Transfer peach juice to 12-inch skillet, add pectin mixture, and whisk until combined. Cook over medium heat, stirring occasionally, until slightly thickened and pectin is dissolved (liquid should become less cloudy), 3 to 5 minutes. Remove skillet from heat, add peach pieces and peach paste, and toss to combine.

Step 5

Transfer peach mixture to dough-lined pie plate. Remove dough strips from freezer; if too stiff to be workable, let stand at room temperature until malleable and softened slightly but still very cold. Lay 2 longest strips across center of pie perpendicular to each other. Using 4 shortest strips, lay 2 strips across pie parallel to 1 center strip and 2 strips parallel to other center strip, near edges of pie; you should have 6 strips in place. Using remaining 4 strips, lay each one across pie parallel and equidistant from center and edge strips. If dough becomes too soft to work with, refrigerate pie and dough strips until dough firms up.

Step 6

Trim overhang to 1/2 inch beyond lip of pie plate. Press edges of bottom crust and lattice strips together and fold under. Folded edge should be flush with edge of pie plate. Crimp dough evenly around edge of pie using your fingers. Using spray bottle, evenly mist lattice with water and sprinkle with remaining 1 tablespoon sugar.

Step 7

Place pie on rimmed baking sheet and bake until crust is set and begins to brown, about 25 minutes. Rotate pie and reduce oven temperature to 375 degrees; continue to bake until crust is deep golden brown and filling is bubbly at center, 30 to 40 minutes longer. Let cool on wire rack for 3 hours before serving.