Combine flour, sugar, baking powder, and salt in a mixing bowl. Cut in shortening until it resembles coarse crumbs. Gradually add cold water to form a dough ball. Roll out and fit into a 9-inch pie plate.

Set the oven to preheat at 325°F (160°C). Ensure your pie crust is ready while the oven heats.

Melt the butter in a microwave-safe bowl for about 1 minute. Allow it to cool to prevent cooking the eggs.

In a large mixing bowl, whisk together the eggs, then add vanilla, flour, pure cane sugar, and dark brown sugar, mixing until well combined. Slowly stir in the cooled melted butter and fold in the chocolate chips and walnuts.

Pour the filling into the prepared pie crust, smoothing it out evenly. Bake for 1 hour until the filling is set but slightly jiggly in the center.

Allow the pie to cool for 30 to 60 minutes before serving warm. Top with vanilla ice cream if desired.