Step 1In a large bowl, whisk together the flour, salt and sugar. Cut in the butter using a pastry cutter or fork, until the butter pieces are reduced to the size of small peas. Drizzle over the water, and gently stir until the mixture starts to come together to form a dough. Knead the mixture lightly to form a cohesive dough. Form the dough into a disk, wrap tightly in plastic wrap and refrigerate at least 1 hour. On a lightly floured board, roll the dough out to a thickness of slightly less than one-fourth inch. Fit the dough into a 9-inch pie plate or tin and trim any excess.
Step 1Heat the oven to 350 degrees. In a large bowl, mash the sweet potatoes. Beat in the granulated and muscovado sugars, then the eggs, melted butter, nutmeg, cinnamon, honey, vanilla and milk. Pour the filling into the prepared pie shell.
Step 2Bake the pie until set and a toothpick inserted into the center comes out clean, 35 to 45 minutes. Cool on a rack to room temperature before serving.