For the best crust, use one of the following: King Arthur’s Italian-style; Arrowhead’s wholewheat pastry flour; White Lily unbleached all-purpose flour.
Grate the frozen butter in a food processor. Add the sugar, fennel seeds, and a pinch of salt and pulse 4 or 5 times. Add the egg and pulse 2 to 3 times to combine.
Add the flour and pulse until crumbly, 3 or 4 times. Dump into a plastic bag, seal, and press the mixture to form a dough, adding 1 tablespoon water if necessary. Chill for 1 hour; form into a flattene