Step 1Par-bake the crust: Heat the oven to 400 degrees, and fit a rack at the lowest part of the oven.
Step 2Line the frozen shell with parchment and fill with pie weights. Bake in a 400-degree oven for 20 minutes, then remove the weights and parchment, prick the sides and bottom several times with a fork and bake until the crust bottom is dry and lightly colored, 10 to 15 minutes more. Set the crust on a rack to cool for several minutes. Brush the sides and bottom with egg white to seal the crust and set aside until the egg white is dried. Meanwhile, reduce the oven temperature to 375 degrees.
Step 3In a large bowl, whisk together the sugar, cinnamon, ginger, nutmeg, allspice, cloves and salt.
Step 4Whisk in the pumpkin until the sugar and spices are evenly incorporated, then whisk in the maple syrup. Whisk in the eggs, 1 at a time, until incorporated. Slowly whisk in the half-and-half.
Step 5Pour the filling into a prepared pie shell, filling it just until it reaches the rim of the crust (depending on the depth of the shell, you might have a little leftover), and bake until the custard is set (the filling should barely jiggle when tapped), 40 to 50 minutes. If the outer rim of the crust darkens too much, tent with a ring of foil, and if the bottom crust browns too quickly, move the pie to a higher rack. Remove to a rack and cool to room temperature before serving.