Thought I would post this while waiting for mine, just out of the oven, to cool. There are a great many varieties of this pie, using different sorts of molasses, eggs sometimes, and other differences in ingredients. This is my recipe:
Dry ingredients:
1 1/2 cups flour
1/2 cup sugar
1 tablespoon cinnamon
1/2 cup shortening or butter
Thoroughly combine first three ingredients in a mixing bowl. Then add and cut in shortening.
Wet ingredients:
1/2 cup molasses
1/2 cup boiling water
1/2 teaspoon baking soda
In a separate bowl add molasses first. Follow with boiling water and then immediately baking soda. Stir until combined; not long.
Make a 9" pie shell. Spoon thin layer of dry ingredients into pie shell, followed by wet, and then alternate dry and wet, finishing with dry. Use two spoons, one for wet and the other for dry.
Bake for 15 minutes at 425 degrees. Decrease oven temperature to 375 degrees and bake about 20 minutes or until set.
Several things:
Your shortening or butter needs to be cold before you try to cut it in.
Cutting in takes two table knives and two hands, one knife in each hand. You slide the knife blades past one another, gradually reducing the size of the shortening or butter hunks and coating them with the dry ingredients.
When you add the baking soda your wet ingredients should foam up quite a bit. If that does not happen, you have a problem.
I use Grandma’s Original Unsulphured Molasses. But options of which molasses to use are many and varied, and opinions differ as to which is the best choice.
Shoo-fly pie is one of life’s good things. Enjoy! 
