Use sharp knife to cut butter into thin slices while still cold, then lay butter on top of dry ingredients in food processor.
Pulse several times until butter is evenly distributed and mixture resembles coarse meal.
Add egg and pulse once or twice until just incorporated, then pulse in enough cream to bring dough together. Remove dough from food processor and press together into one mass.
Divide dough into 2 uneven pieces, about two-thirds and one-third.
Form each into ball, and flatten each ball into thick disk.
Place each disk between 2 sheets of wax paper, and roll until about 1/8 inch thick.
Ease larger circle into 9- or 10-inch pie pan and trim edges.
Cut smaller circle into strips about 1/2 inch wide.