Put flour, sugar, and salt into a food processor and pulse four or five times to mix. Scatter butter on top. Process for 8 seconds more. Add cold water all at once and process for 6 to 8 seconds, or just until crumbs form. Stop before dough clumps on blade.
Turn mixture out onto wax paper and gather into a smooth ball. Knead once or twice. Chill for 30 minutes to 1 hour before rolling out.