Heat the milk, heavy cream, vanilla extract, and sugar in a large saucepan to 175°F. Dissolve the unflavored gelatin powder in ¾ cup hot water and stir it into the vanilla mixture until combined. Rinse the 9-inch bundt cake pan with cold water, pour in the vanilla jello pudding mixture, transfer the bundt cake pan to the refrigerator, and chill for at least 2 hours.
Heat the water, lemon juice, sugar, and vanilla extract in a large saucepan to 175°F. Dissolve the unflavored gelatin powder in ⅓ cup hot water and add it to the lemon mixture. Once combined, remove the transparent jello mixture from the heat and let it cool. Remove the set vanilla jello pudding from the refrigerator, divide it into 8 equal sections, and remove every other slice from the bundt cake pan.
Place the chopped pineapple, chopped mango, chopped strawberries, and green grapes in the gaps left in the bundt cake pan.
Pour the transparent jello mixture over the fruit, transfer the bundt cake pan to the refrigerator, and chill for another 2 hours, preferably overnight.
Once the cake has set, remove it from the refrigerator and flip it over onto a serving platter. Fill the center with fresh fruit and dig in!
