Combine the oatmeal cookie crumbs and melted butter and firmly press the mixture into the bottom of a greased 9-inch springform cake pan.
Rinse out the inside of a 16.9 fl oz plastic bottle with a grooved bottom and cut off the bottom 2 inches of the bottle. Repeat with 5 more bottles for a total of 6 grooved bottle pieces.
Add the sugar, egg yolks, milk, butter, vanilla, and corn starch to a saucepan over low heat and whisk until a smooth cream forms. Squeeze the liquid out of the soaked gelatin sheets and stir them into the mixture until dissolved.
Pour some of the vanilla pudding over the cookie crust in the springform cake pan, about 1-inch deep, and let cool. Grease the outsides of the 6 grooved bottle pieces and gently push the tops into the pudding so that the grooved ends are facing up.
Pour the remaining vanilla pudding over the grooved bottle pieces in the springform cake pan and refrigerate for at least 3 hours.
Once the pudding has set, carefully remove the grooved bottle pieces. To do so, unfold a paper clip and bend the end into a slightly curved shape. Heat the curved end with a lighter, press it into the plastic until it hooks under the middle, and gently lift the bottle piece up.
Puree ¾ of the fresh raspberries, ¾ of the diced kiwi, and ¾ of the diced mango separately and fill 2 of the flower cavities with raspberry puree, 2 with kiwi puree, and 2 with mango puree. Decorate the fruit flower petals with the remaining corresponding fruit.
Decorate the middle of the vanilla pudding flower pie with fresh raspberries, diced mango, and fresh mint leaves.