Raspberry Fool is an old, old, old recipe (dating back to 1598!) These days, this vintage recipe involves folding macerated raspberries into whipped cream to make a delicious mousse-like treat. In this Raspberry Fool Sheet Cake, my favorite yellow sheet cake is topped with fluffy raspberry fool and crushed shortbread cookies. It's perfect for a crowd at a potluck or picnic!
Make the cake: Preheat the oven to 375 degrees and grease a 15 x 10 x 1″ baking sheet. In a medium saucepan over medium heat, bring the butter and water to a boil. In the meantime, in a separate large bowl, whisk together the cake flour and sugar before adding the eggs, sour cream, almond extract, vanilla extract, baking soda, and salt. Mix to combine. While mixing, slowly pour in the boiling butter and water mixture. Mix to combine completely. Your batter will be very runny. Pour the batter into the prepared baking sheet.
Bake at 375 degrees for 17-22 minutes or until a toothpick inserted in several places comes out with a few moist crumbs (don’t wait for the top to get golden brown, necessarily — mine stayed pale). Cool completely.
Make the raspberry fool frosting: Stir together 2 cups of the raspberries, sugar, and water in a medium bowl and let this sit for 15 minutes. Beat the heavy whipping cream and powdered sugar together to soft peaks. Mash the raspberry mixture until it’s completely mixed together. Spoon half of this mixture into the cream and fold it in just 1-2 times. Frost completely cooled cake with this mixture, drizzling remaining raspberry mixture over the top and swirling it gently. Top the cake with crushed cookies and remaining raspberries for garnish.
Recipe by Willow Bird Baking at http://willowbirdbaking.com/2017/08/01/raspberry-fool-sheet-cake/