Talk about a fun dessert! It looks like a sheet cake on top, but there are actually vanilla-coconut cupcakes underneath the fresh berries and fluffy whipped-cream frosting. It's easy to make and even easier to serve—no slicing required.
Preheat oven to 350 degrees. Line a standard muffin tin with paper liners. Whisk together cookie crumbs, flour, baking powder, and salt.
Beat butter with granulated sugar on medium speed until pale and fluffy, about 1 minute. Beat in eggs, one at a time. Reduce speed to low and add flour mixture in 3 batches, alternating with milk, beginning and ending with flour mixture and beating until combined after each addition. Fold in coconut.
Divide batter among cups. Bake until cupcakes are golden brown and centers bounce back when gently pressed, 22 to 24 minutes. Let cool completely in tin on a wire rack.
Add 2 tablespoons water to a small saucepan. Sprinkle with gelatin; let stand until thick, about 5 minutes. Gently heat over medium until gelatin has dissolved. Remove from heat; let cool 5 minutes (but don't let it set).
Beat together cream, confectioners' sugar, and vanilla on medium speed until very soft peaks form, 1 to 2 minutes. Add gelatin mixture; beat on medium until stiff peaks form, about 1 minute more.
Remove cupcakes from tin and arrange on a platter in a three-by-four rectangle. Spoon frosting over each row of cupcakes; using an offset spatula, smooth to cover tops, forming a rectangular shape. Refrigerate at least 1 hour and up to 3 hours. Sprinkle with berries before serving.