Directions

1. Preheat oven to 350 degrees. Make dough: In a food processor, pulse almonds until finely ground. Add sugar, flour, zest (if desired), and salt; pulse until combined. Add butter, pulsing until coarse crumbs form with no large butter lumps (dough should clump together when squeezed with fingers).
2. Immediately transfer dough to a 9-inch tart pan with a removable bottom. Using a measuring cup, evenly press dough in bottom and up sides of pan.
3. Bake in center of oven until golden brown and firm to the touch, about 20 minutes. Transfer to a wire rack to cool completely, about 1 hour.
4. Make ganache: Place chocolate in a large mixing bowl. In a small saucepan, bring cream to a boil. Pour hot cream, through a sieve, over chocolate. Stir until smooth and creamy in texture. Mix in vanilla.
5. Pour chocolate mixture into center of cooled tart shell (if chocolate is lumpy, pass through a sieve). Let stand until set, about 2 hours, or chill for 1 hour.