Heat oven to 400°F (if using dark or nonstick pan, heat oven to 375°F). In food processor, place 1/4 cup hazelnuts and 1 tablespoon sugar; cover and process 45 seconds or until finely ground. Add flour and 1/2 teaspoon salt; cover and process 5 seconds or until mixed. Add butter; cover and process, pulsing on and off 5 to 10 times, until mixture looks like coarse crumbs. Add water, 1 tablespoon at a time, pulsing on and off, until mixture starts to hold together.