Preparing the Crumb Topping: In a large mixing bowl, combine the flour, 1 cup of brown sugar, and baking soda. Cut in the cold butter, tallow, or lard using a fork or pastry blender until the mixture resembles coarse crumbs.
Measure out 3 cups of this crumb mixture and set it aside. This will be folded into the wet bottom filling.
Keep the remaining crumb mixture aside for topping the pies.
Make the Wet Bottom Filling: In a separate mixing bowl, whisk together the molasses, hot water, baking soda, and 1/2 cup of brown sugar until the sugar is mostly dissolved. Gradually whisk in the beaten eggs until well combined.
Add the reserved 3 cups of crumb mixture to the wet ingredients and stir until just combined. Be careful not to overmix. The batter will be quite liquid.
Assemble and Bake the Pies: Place the unbaked pie shells on a baking sheet for easier handling. Pour the wet bottom filling evenly into the pie shells. The amount will depend on the size of your shells; you should aim to fill them almost to the top.
Sprinkle the remaining crumb topping evenly over the filling of each pie.
Bake the Pies:Preheat your oven to 425°F (220°C). Bake the pies at 425°F (220°C) for 10 minutes. This initial high heat helps to set the crust.
Reduce the oven temperature to 350°F (175°C) and continue baking for an additional 45 minutes, or until the filling is mostly set but still has a slight jiggle in the center. The crumb topping should be golden brown.
If the crust starts to brown too quickly, you can loosely tent the edges with aluminum foil.
Cool and Serve: Let the pies cool completely on a wire rack for at least 2-3 hours before slicing and serving. This allows the wet bottom to fully set. Enjoy your delicious Wet Bottom Shoo-Fly Pie! It's wonderful on its own or with a dollop of whipped cream or a scoop of vanilla ice cream.