This article is adapted from the November 18, 2024, edition of Gastro Obscura’s Favorite Things newsletter. You can sign up here. When I recently Googled “Thanksgiving salad,” the results were recipes for vibrant, fresh vegetable mixtures, thoughtfully tossed with seasonal nuts and savory dressings. This was not what I wanted to see. Googling “Thanksgiving salad with Cool Whip,” on the other hand, delivered the recipes I was looking for: the fanciful sweet salads that 20th-century Americans concocted out of Jell-O, canned fruit, and whipped topping. Every Thanksgiving, my grandma Lois…