Hood, who lives in Illinois, says it's a mystery where Grandma Caroline, who has since passed away, got the wildly popular recipe.
"I'm betting that like a lot of baking housewives of her time, it was on the side of a package or given by a friend," Hood told TODAY Food. "The lemon squares were her no-fuss treat … she used a very specific deep aluminum pan that my sister has since inherited, and always brought the powdered sugar in an old-fashioned sifter to dust on just before serving."
Hood says she shared the recipe in r/Old_Recipes after following the subreddit for a while, but had no idea it would become a viral hit within the group. Since posting a photo of the typed recipe, a separate subreddit, r/JustHoodsLemonBars, was then established, where more than 12,000 members share photos of their lemon bar creations.
The bars have been tweaked by some fans, with strawberries pressed into the surface or orange zest added to the lemon filling. But Hood says Grandma Caroline was a purist when it came to her lemon bars.
"Caroline would not have approved of changes people have made," said Hood. "She disapproved whenever her grandkids messed with her recipes.
"But I think she would have been secretly pleased by how much people love them."
There was, however, one tweak even Grandma Caroline found useful: Substituting bottled lemon juice for fresh.
"This isn’t in the recipe, but she was all about bottled, pre-squeezed lemon juice," said Hood. "She raised five kids, partially on her own, so she liked quick and easy recipes."
Hood said when fellow Redditors say the lemon bars are too sweet, she recommends making the Grandma Caroline-approved switch to store-bought juice.
"Bottled lemon juice is much more tart, especially once baked," she explained. "My sister and I prefer to double the juice, and I like some zest in there, too."
Eager to try Grandma Caroline's recipe in my kitchen, I gathered the surprisingly simple ingredients: Flour, butter, sugar, salt, lemon juice, eggs and powdered sugar are all that's required to achieve the lemony goodness.
The first steps of the recipe involve creaming together flour, butter and powdered sugar to make a crust. After baking the crust for 20 minutes, the bright, sugary mixture of lemon juice, flour, salt and sugar gets spread on top. The pan then returns to the oven for 25 minutes.
Once the lemon bars cooled, I used a sifter to cover them with powdered sugar, just like Grandma Caroline did.
These citrusy sweet lemon bars were, hands down, my favorite recipe I've made from the r/Old_Recipes subreddit so far. They were light, lemony perfection and they'll definitely be on my go-to recipe list.
Hood said seeing people love her grandmother's recipe makes her family thankful for the small way her memory lives on.
"I feel like every time someone makes these bars, it reminds us of her: sour at first, but sweet in the end."