For the Crust

1. Place butter, sugar, and flour into a food processor or blender, and pulse until you have coarse (pea sized) crumbs. Scrape down sides as needed. Slowly add chilled water and pulse, until the dough begins to come together. It should still be slightly crumbly. Pour the dough onto a piece of plastic wrap and knead a few times to bring together. If the dough is too crumbly, sprinkle a little water over it and knead again. Wrap the dough up in the plastic wrap and chill for at least 3 hours.
2. To roll out the crust, allow the dough to sit at room temperature for about 15 minutes. Then unwrap and place the dough on a well-floured surface. Roll the dough out so you have a large circle that is a few inches wider than your pie tin. Be patient as you roll, turning the dough to check for sticking and adding more flour as needed. Roll the dough around the rolling pin to transfer it to the pie dish.
3. Without stretching the dough, place it into the pie dish, and trim excess dough around the edges, leaving about a 1-inch overhang. Roll the edge under, and then crimp.

For the Filling

1. Preheat oven to 350 degrees.
2. Trim both ends off the lemon, and cut into quarters. Add lemon, butter, sugar, eggs, and vanilla extract to a blender, and blend until smooth and creamy. Pour into unbaked pie shell, and bake at 350 degrees for 35-40 minutes. Cover edges of pie with tin foil if they brown before the pie is done.
3. Allow to cool completely before slicing. Can be refrigerated and served chilled or at room temperature. Dust with powdered sugar just before serving.