1 3/4 cups water
1/2 cup granulated sugar
1/4 cup cornstarch
1 large egg
1/4 cup lemon juice
2 teaspoons grated lemon rind
15 4 3/4- by 2 1/2-inch graham crackers, broken in half
3/4 cup heavy cream
1 tablespoon confectioners' sugar
1/4 teaspoon lemon extract
In 2-quart saucepan, heat 1 1/4 cups water to boiling. In small bowl combine granulated sugar, cornstarch, egg, and remaining water.
Gradually stir cornstarch mixture into boiling water. Heat to boiling, stirring constantly until thickened. Remove from heat; fold in lemon juice and 1 teaspoon grated rind. Set aside until pudding is cool enough to handle—about 20 to 30 minutes. Wrap and reserve remaining lemon rind.
Frost graham crackers together with lemon pudding, in stacks of 5. Spoon a little pudding in a 2-inch wide strip down center of serving platter. Using more pudding, assemble stacks of graham crackers, end to end, in a row of pudding on platter. Spread any remaining pudding over top and sides of graham cracker loaf. Wrap tightly and refrigerate 6 to 8 hours.
To serve: In small bowl with electric mixer, beat cream, confectioners' sugar, and lemon extract until stiff. Frost loaf with whipped cream; sprinkle with remaining grated lemon rind over top. Slice diagonally.
