1. Preheat oven to 350°.
2. Fit dough into a 9-inch pie plate. Fold edges under; flute.
3. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Place flour and next 3 ingredients (through salt) in a food processor; process until a sandy texture. Remove and set aside 1/2 cup flour mixture from food processor, reserving remaining mixture in food processor bowl.
4. Combine egg and vanilla in a medium bowl, stirring with a whisk. Gradually add molasses, stirring with a whisk. Stir baking soda into 3/4 cup boiling water. Add baking soda mixture to molasses mixture, whisking until blended. Stir in flour mixture from food processor bowl, stirring with a whisk until smooth. Pour mixture into prepared crust. Sprinkle with reserved 1/2 cup flour mixture.
5. Bake at 350° for 37 minutes or until slightly puffed and surface begins to crack. Cool completely on a wire rack. Serve at room temperature.