In a large bowl, add the flour, shortening, and salt.

Using a pastry cutter, cut the flour into the shortening until it resembles small pea-sized pieces.

In a 1-cup measuring cup, add the egg and beat until it's a light lemon color.

Add the vinegar and water to the beaten egg and stir well.

Add the egg mixture to the flour mixture and stir until well blended.

Use your hands to finish mixing if needed, but do not knead or overwork the dough—mix just until blended.

Divide the dough into two equal pieces.

Take one piece and place it on a solid surface.

Sprinkle a little flour on top, and use a rolling pin to roll it out. Add more flour as needed.

Roll until the dough is large enough to fit in the pie plate with a slight overhang.

Gently press the dough into the pie plate, pinch the edges, and trim any excess dough.

Set the crust aside.

In a heavy-bottomed medium saucepan, add butter and chocolate chips.

Melt the butter and chocolate together, stirring until completely melted and hot (but not boiling).

Remove from heat.

Stir in sugar, flour, milk, corn syrup, vanilla, and eggs.

Mix until well combined.

Pour the filling into the prepared pie crust.

Bake at 350°F (175°C) for 30 minutes.

Remove the pie from the oven and place it on a wire rack to cool completely.

Once cool, top with whipped cream.

Serve and enjoy!