Fit dough into a 9-inch pie plate. Fold edges under; flute.
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.
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.
Bake at 350 for 37 minutes or until slightly puffed and surface begins to crack. Cool completely on a wire rack.