Place the butter, vanilla, powdered sugar and flour in a mixer on low speed and mix until small crumbles form. Press the dough into parchment paper lined half sheet pan (18"x13") and bake at 350°F for 20 minutes.
While the crust bakes in the oven, combine the eggs, sugar, lilikoi puree, salt and baking powder in a bowl and mix until smooth and frothy. Pour the mixture over the hot crust and bake for 35 minutes at 325°F. Chill, cut and serve topped with powdered sugar or whipped cream and berries.
This dessert bar can be made with any fruit puree, but you may need to adjust the sugar if the fruit puree is sweeter than the lilikoi. Use fruits in season to garnish these dark yellow bars, especially red raspberries or strawberries. If you don't have a half sheet pan (18"x13"), you can use two 9"x13" pans or one 9"x13" pan and just use half of the ingredients.