A “blondie” is a “blond brownie” (or “blonde brownie"), a light-colored brownie. Chocolate is replaced by brown sugar and vanilla extract to give them the lighter color.
The “brownie” was probably named after a popular fictional character of the 1890s, and “blondie” also perhaps took from the popularity of Chic Young’s “Blondie” comic strip (1930 - present). “Blondies” are cited in print from at least 1941.
See also “chocolate brownie” and “Broadway brownie.”
Wikipedia: Blondie (comic strip)
Blondie is a popular comic strip created by Murat Bernard “Chic” Young and syndicated by King Features Syndicate. It has been published in newspapers since September 8, 1930. The success of the comic strip led to a long-run Blondie film series (1938-1950) and a popular Blondie radio program (1939-1950).
Chic Young drew Blondie until his death in 1973, when the control of the strip passed to his son Dean Young. Dean Young has collaborated with a number of artists on the strip, including Jim Raymond, Mike Gersher, Stan Drake, Denis Lebrun and most recently, John Marshall. Through these changes, Blondie has remained popular, appearing in more than 2300 newspapers in 55 countries and translated into 35 languages, as of 2005. Blondie celebrated its 75th anniversary in 2005.
19 December 1941, Dallas Morning News, section 2, pg. 6:
Blond Brownies are an exciting and flavorful new version of the ever-popular Brownie cookie. The secret of their blondness lies in the omission of chocolate from the cookie batter but the chocolate flavoring is given to these treats by using chipped chocolate and sprinkling it over the top of the cookie batter before the Brownies go into the oven. The heat of the oven melts the chocolate to glistening smoothness.
To make them, the following ingredients are required: Three eggs, two and one-half cups sifted flour, one-half teaspoon salt, one cup chopped nuts, three ounces chipped semi-sweet chocolate. Beat the eggs well. Add sugar gradually, beating until well mixed. Add vanilla. Sift flour and salt together and stir into egg mixture. Add nuts. Pour into a well-greased pan, nine by twelve inches and two inches deep. Sprinkle the chipped chocolate over the batter. Bake in a moderate oven, 350 degrees Fahrenheit, twenty-five minutes. Makes about four dozen squares.
15 January 1942, Syracuse (NY) Herald-Journal, pg. 29, col. 3:
Three eggs, 2 1/2 cups brown sugar, 1 teaspoon vanilla extract, 1 1/2 cups sifted flour, 1/2 teaspoon salt, 1 cup chopped nuts, 3 ounces chipped semi-sweet chocolate.
Beat eggs well. Add sugar gradually, beating until well mixed. Add vanilla. Sift flour and salt together and stir into egg mixture. Add nuts. Pour into well greased 9x12x2 pan. Sprinkle the chipped chocolate over the batter. Bake in moderate oven (350 degrees F.) 25 minutes. Yield: About four dozen squares 1 1/2 x 1 1/2.
27 May 1943, Salamanca (NY) Republican-Press, pg. 5, col. 2:
(Light Colored Brownies)
4 tablespoons shortening
3/4 cup dark brown sugar
2 eggs, beaten
1/4 cup cream
1 teaspoon vanilla
1/2 teaspoon salt
1/2 cup semi-sweet chocolate (small pieces)
1 cup flour
1/2 teaspoon baking powder
1/2 cup nuts
Cream shortening and sugar. Add rest of ingredients and beat 2 minutes—this beating is important. Pour into shallow pan and bake 25 minutes in moderate oven.
2 October 1953, Dallas Morning News, section 2, pg. 6:
Bake a batch of Blonde Brownies to send to that girl or boy away at school. Send enough so there will be plenty to pass around to dormmates. Sift together 1 cup sifted enriched flour, 1 1/2 teaspoons baking powder, and 1/2 teaspoon salt. Melt 1/4 cup shortening. Cool and add 1 1/2 cups brown sugar and 2 eggs, beaten. Mix well. Add flour mixture gradually, mixing until smooth. Add 1/2 teaspoon vanilla extract, 1 cup chopped nuts and 1/2 cup chocolate bits (3 ounces). Spread in greased pan, 7x11 inches. Bake in moderate oven (350 degrees F.) about 30 minutes. Cut into bars. Makes 21 bars, about 1 1/2x2 inches. When bars have cooled, wrap them individually in waxed paper or aluminum foil to keep them fresh while traveling.
New England Cookbook
by Eleanor Early
New York: Random House
Blondies are fat little sister of Brownies. There is nothing old-fashioned or regional about Blondies. They just happen to be (Pg. 171—ed.) popular in New England, and that is how they found their way into this book.