I do not know "from whence this recipe cometh" but my Mama made these a few times when I was young. They are delicious and when I became an adult I made them at holiday time. My Uncle Ed became a huge fan of them. They are very sweet so eat sparingly.
1Line a 9x13" baking pan with the graham crackers
Place next 4 ingredients in a small saucepan and bring to a boil
After it has boiled for a minute, add last four ingredients
Spread mixture onto graham crackers
Gently press more graham crackers on to filled ones
2Frost and let set for about an hour
Cut in to bars