This twist on a classic apple pie uses real maple syrup to sweeten the filling, which provides deep flavor as well as antioxidants and minerals. If you can't find Pink Lady apples, swap in Honeycrisps, Galas, or Fujis.
Prepare crust: Pulse whole-wheat flour, all-purpose flour, sugar, and salt in a food processor until combined, about 5 pulses. Add cold butter, pulsing until mixture is crumbly, 10 to 15 pulses. Add yogurt, and pulse until a dough forms, about 15 pulses. Shape dough into 2 disks, and wrap each tightly in plastic wrap. Refrigerate until chilled, about 30 minutes. (Dough can be made up to 2 days in advance; if it is, before rolling out, let stand at room temperature 20 minutes.)
Place a rack in lower third of oven and preheat to 350°F. Remove 1 dough disk from refrigerator and unwrap. Roll dough into a 13-inch circle on a lightly floured surface. Fit dough into a 9-inch pie plate, and place in refrigerator until ready to use.
Remove remaining dough disk from refrigerator and unwrap. Roll dough to 1/8-inch thickness on lightly floured parchment paper. Cut into 8 to 10 (1-inch-wide) strips. Transfer dough strips and parchment paper to a large plate or baking sheet, and chill until ready to use.
Prepare filling: Stir together apple slices, maple syrup, flour, lemon juice, cinnamon, nutmeg, and salt in a large bowl.
Spoon filling into crust in pie plate, mounding apples toward center of pie. Arrange dough strips over filling in a lattice design. Trim off excess dough, and crimp edges to seal. Brush crust with beaten egg, sprinkle with turbinado sugar.
Bake on bottom rack of oven until crust is golden brown and filling is bubbly, 1 hour and 10 minutes to 1 hour and 20 minutes. (If needed, loosely cover with foil during last 20 to 30 minutes of baking to prevent excess browning.) Transfer to a wire rack and cool completely, about 2 hours, before serving.