HEAT oven to 400ºF.
"BUTTER and flour bottom and sides of a 9” tart pan with a removable bottom.
UNROLL pie crust and gently press into bottom and sides of pan. Trim excess from top.
PRICK bottom of pastry with tines of a fork. Using a pastry brush, brush crust with egg white.
BAKE for 10 minutes, until egg white has set. Let cool 10 minutes.
BEAT eggs lightly in a medium bowl. Whisk in the cheeses, scallions, salt, pepper and ham.
POUR into cooled crust and bake for about 18 minutes, until mixture has set and top is golden.
COOL tart for 10 -15 minutes and then remove from pan.
SPRINKLE with parsley and cut into wedges to serve warm or at room temperature.