Pre-heat oven to 350°F.
In the bowl of a stand mixer fitted with a paddle attachment, combine butter and icing sugar. Mix on low speed until combined, about 1 minute.
Add egg yolks and mix until incorporated, scraping down the sides of the bowl as necessary.
Add half the flour along with the salt and mix on low speed just until the flour is incorporated, about 30 seconds. Add remaining 1/2 cup of flour and mix just until flour is no longer visible, about 1 minute.
Roll out dough between 2 pieces of parchment paper to fit tart tin, about 1/4-inch thick. Loosen parchment from both sides of dough and turn over onto 4-inch x 14-inch tart tin. (Tart tin should ideally have a removable bottom.) Shape dough to tin; trim and discard excess dough.
Perforate dough with a fork, line tart with parchment paper and fill with pastry weights. Bake for 8 minutes then remove pastry weights and return tart to oven for an additional 6 minutes.
Remove from oven and let cool on rack. Remove from tart tin.
Meanwhile, in a small bowl, mix together a splash of milk, corn starch, sugar and salt.
In a small pot, add remainder of milk and heat over medium-high heat. Whisk eggs into corn starch mixture. When milk comes to a boil, slowly and gradually add the milk to the egg and corn starch mix, whisking constantly in order to temper the eggs.
Return entire mixture to pot, add vanilla, and place over medium-high heat, whisking constantly until thick and bubbling for at least 15 seconds.
Remove from heat. Pass through sieve with a spatula and transfer to a round cake pan. Place plastic wrap directly on top of the pastry cream and chill until fully cooled and set, approximately 2 hours.
Remove pastry cream from refrigerator and stir. Using a small offset spatula, spoon or piping bag, fill bottom of tart shell with an even coating of pastry cream.
Working from the corners toward the middle, make lines of fruit as desired using blueberries, kiwi, raspberries, mango and strawberries.
In a small saucepan over low heat, warm apple jelly until it just reaches a liquid consistency. Do not overheat. Spoon or brush a thin, even layer of jelly over fresh fruit. Refrigerate until ready to serve.