Roll half of pastry to 1/8-inch thickness on a lightly floured surface, and fit into a 9-inch pie plate. Trim excess pastry around edges. Fold edges under, and flute. Prick bottom and sides of shell with a fork.
Roll remaining half of pastry into an 8-inch circle, and place on a baking sheet. Bake pastry shell and pastry circle at 425° for 12 to 15 minutes or until golden brown. Cool.
Combine 3/4 cup sugar, flour, and salt in top of a double boiler; stir in milk, egg yolks, and egg, mixing well. Cook over boiling water, stirring constantly, 20 minutes or until very thick and smooth. Remove from heat, and add 1 teaspoon vanilla. Let cool.
Beat whipping cream in a small mixing bowl until foamy; gradually add 2 tablespoons sugar, 1 tablespoon at a time, beating until soft peaks form. Stir in 1/4 teaspoon vanilla.
Fold one-fourth whipped cream into custard mixture. Pour half of custard into baked pastry shell. Top with baked pastry circle and remaining custard. Cover with remaining whipped cream. Garnish with chopped maraschino cherries and pecans. Cool completely.
Note: For a more festive pie, arrange cherries in the shape of a Christmas tree on top of pie.