“Flapper Pie” is named after the 1920s flappers. It is a Graham cracker vanilla custard pie topped with meringue.
 
The origin of flapper pie is uncertain, but a recipe from Mrs. Thomas Silk of Huntington, California, was printed in the Cleveland (OH) Plain Dealer on February 21, 1930.
 
Flapper pie quickly became popular in the Canadian provinces of Alberta and Saskatchewan, where it is still popular. The Edmonton (Alberta) Journal, on July 14, 1931, reported that flapper pie won a prize. Christie’s Honey Maid Graham Wafers put a flapper pie recipe on the box, further popularizing the pie in this region in the 1960s.
   
   
Wikipedia: Flapper pie
Flapper pie is a vanilla custard pie topped with meringue (or sometimes whipped cream in South Saskatchewan). The Graham cracker cream pie dates back to the 19th century but entered Western Canadian pop culture in the 20th century as flapper pie.
 
The pie is a staple of the Canadian prairie culture. At the Salisbury House chain of restaurants in Winnipeg, it is sold as “wafer pie.”
   
2 September 1924, Chicago (IL) Daily Tribune, pg. 9, col. 1 ad:
We have an attractive Flapper Pie and a timely ‘Going Away to School Pie,” which is also unique.
(Marshall Field & Company.—ed.)
 
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2 January 1930, Bismarck (ND) Tribune, “Barbs,” pg. 4, col. 7:
The household page gives a recipe for “flapper pie.” We suppose it will be conspicuous for its crust. Or maybe we should expect a fine frosting.
   
21 February 1930, Cleveland (OH) Plain Dealer, “Today’s Winners,” pg. 18, col. 3:
Flapper Pie.
12 graham crackers
1/4 c. melted butter
1/2 c. granulated sugar
3 T. cornstarch
3/4 c. brown sugar
2 c. milk
2 eggs
1 T. melted butter
1 t. vanilla
Roll crackers fin. Add sugar, butter and mix well. Place half of mixture in pie pan, molding it to pan like pastry. Place cornstarch, brown sugar, milk, egg yolks and the tablespoon of melted butter in double boiler and cook until thick. Add vanilla.
 
Fill lined pan with mixture. Beat egg whites stiff, add two tablespoons granulated sugar for each egg white, place on top of custard. Cover meringue with remaining half of cracker mixture. Brown at 300 degrees. Serve cold.
MRS. THOMAS SILK.
Huntington Park, Cal.
 
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11 May 1930, Chicago (IL) Sunday Tribune, “The Tribune Cook Book” by Jane Eddington, pt. 6, pg. 4, col. 2:
Flapper Pie.
(...)
Fourteen Graham crackers rolled fine (save out a few of the crumbs), and made into a paste with four tablespoons of butter. Line a pie tin with this paste, fill it nearly full with sliced bananas, pour over it a custard made with the yolks of two eggs. Put meringue made of the whites of two eggs over that and then sprinkle the cracker crumbs that have been saved out from those rolled. It seems to me that this banana nougat in a paste like this might well be substituted for the sliced bananas and the custard.
 
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1 August 1930, The Oklahoma Weekly Leader (Oklahoma City, OK), “Household Hints,” pg. 2, col. 7:
Flapper Pie
Two level spoons butter, two cups brown sugar, six eggs, one large size can of milk, one teaspoon vanilla, two tablespoons flour, two tablespoons cornstarch, and one dozen graham crackers.
 
Add enough water to milk to make one quart. Place sugar and milk (reserving enough to make a paste when mixed with flour and cornstarch) in pan. Beat yolks of four eggs and whites of two and add to sugar and milk, then add butter and cook in double boiler till thick. Cool and add vanilla. Roll graham crackers and place a thick layer in a pan. Pour filling over them and add the other four egg whites beaten stiff. Then top with rest of crackers and brown lightly. Chill and serve.
   
Old Fulton NY Post Cards
15 November 1930, Medina (NY) Daily Journal, “The Cook’s Nook,” pg. 3, col. 7:
FLAPPER PIE (Delicious)
Mrs. Alice Watt, West Center Street
20 Graham crackers
1/4 cup granulated sugar
1/2 cup melted butter
Crush crackers fine, mix with butter and sugar. Put one-half of crumbs on a greased pie tin.
CUSTARD FOR FILLING
2 cups milk
3 egg yolks
Teaspoon vanilla
2 tablespoons cornstarch
1-4 cup sugar
Teaspoon butter
Pinch salt. Cook until thick. Put pie in crust.
Beat egg whites with one tablespoon water and three of sugar until very stiff. Spread on pie sprinkle the remainder of cracker crumbs on top; brown in moderate over 20 minutes. Should be served very cold.
   
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14 July 1931, Edmonton (Alberta) Journal, pg. 7, col. 5:
Mrs. J. A. Stevenson Wins Prize for Flapper Pie
 
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21 September 1932, Napa (CA) Journal, “Louise Lane Presents Pet Recipes to Napa Women,” pg. 3, cols. 4-5:
FLAPPER PIE
12 large graham crackers
1/2 cup sugar
1/4 cup melted butter
3 tablespoons corn starch
3/4 cup brown sugar
2 cups milk
2 egg yolks
1 teaspoon vanilla
2 egg whites
4 tablespoons sugar
1 tablespoon melted butter
Method: Roll crackers fine; add sugar and butter and mix well. Place 1/2 mixture in pie pan, molding it to pan as if it were pastry. Place corn starch, brown sugar, milk, egg yolks and the 1 tablespoon melted butter in double boiler, cook until thick. Add vanilla. Fill the lined pie pan with mixture. beat egg whites until stiff, add the 4 tablespoons of sugar and place on top of filling. Sprinkle meringue with remaining half of Graham cracker mixture. Brown in oven at 300 degrees F. Serve cold.
 
22 November 1932, Chicago (IL) Daily News, pg. 14, col. 5:
The Crust for a Flapper Pie Is a New One
It Is Made of Zweiback, and Enriched with Nuts and Butter.
By EDITH G. SHUCK.
 
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4 May 1934, Calgary (Alberta) Daily Herald, pg. 2, col. 1 ad:
FLAPPER PIE
(Independent Biscuit Company Ltd.—ed.)
   
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15 March 1937,  Pottstown (PA) Mercury, pg. 7, col. 5:
SECOND PRIZE
WON BY
MRS. JOHN DUSKO
223 N. Evans St.
FLAPPER PIE
20 graham crackers
1/4 lb. melted butter
1 tablespoon sugar’Mix all together and line a pie plate with this mixture, reserving a few crumbs for top of pie.
   
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22 July 1939, Saskatoon (Saskatchewan) Star-Phoenix, “The Recipe File,” The Prairie Pals, pg. 4, col. 4:
FLAPPER PIE
14 honey wafers, rolled fine
1/2 cup granulated or brown sugar
1/4 cup melted butter
1/2 tsp. ground cinnamon.
Mix together and remove 1/2 cup mixture for top of pie, using the balance to line the bottom of the tin. Then add filling made as follows:
2 cups milk
2 egg yolks
2 tbsps. corn starch
1/4 cup granulated sugar
1 teaspoon vanilla
(A lemon filling is good too).
Cook until thick and spread while hot. Then cook two eggs whites stiff and beat in three tablespoons icing sugar and spread on top of filling. Sprinkle remainder of crumbs over top and bake in a slow oven at 250 degrees, for 20 minutes.
A Cook,
WILLIAM WILLIAMS.
 
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28 February 1948, Edmonton (Alberta) Journal, Annual Cook Book sec., pg. 4, col. 3 ad:
A Recipe For
DELICIOUS FLAPPER PIE
(Sunland Graham Wafers.—ed.)
   
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22 April 1992, Times-Colonist (Victoria, BC), “Lost & Found,” pg. C3, col. 2:
Remember we were asking if anyone knew the origin of flapper pie? Betty Barker of Sidney, and Iris Kellerman of Youbou both agree that they first saw the recipe on a box of Christies Honey Graham Wafers, some 30 years ago.
 
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21 January 2015, Windsor (ON) Star, “Canada’s Top Trending Recipes for 2014: 13 of the country’s favourite recipe broken down by province, territory” by Laura Brehaut, pg. C1, cols. 1-2:
Saskatchewan
Flapper pie, Saskatchewan’s top trending recipe for 2014, is a simple vanilla custard pie with a graham-cracker crust and meringue topping. It’s a Prairie favourite and is assumed to have been named during the flapper era of the 1920s, although by who and where is anybody’s guess.