01 - Set oven temperature to 400°F (200°C).
02 - Place the unbaked pie crust into a 9-inch pie pan and crimp the edges.
03 - Pour 1 1/2 cups water directly into the prepared pie crust.
04 - In a mixing bowl, blend 3/4 cup granulated sugar with 3 tablespoons all-purpose flour until evenly mixed. Sprinkle this mixture over the water in the pie crust.
05 - Drizzle 1 teaspoon vanilla extract and a pinch of salt over the surface. Slice 4 tablespoons unsalted butter into thin pats and distribute evenly.
06 - Place pie on the lower rack and bake for 30 minutes at 400°F (200°C).
07 - Reduce oven temperature to 375°F (190°C) and continue baking for 20 minutes, until the crust is golden and filling is just set with slight jiggle.
08 - Remove pie from oven and let cool to room temperature. Refrigerate for at least 2 hours before slicing to allow proper setting.