Pineapple Filling: Drain the pineapple well over a bowl, pushing on it through a fine mesh strainer to push out as much juice as possible. (Save the pineapple juice to drink or for making pineapple mojitos!) Mix together the sugar, cinnamon and salt, set aside.
In a saucepan place the strained pineapple and cook over medium heat until all the juice is gone and pineapple appears dry; about 5 minutes. Add the sugar/cinnamon/salt mix and stir constantly over medium heat and cook until all the juice is absorbed, it appears dry and sticky. (visually you are looking for a mixture that comes together when you stir and push it around with the spatula). This will take about 10-15 minutes. Add in the corn syrup and cook again until mixture appears sticky and dry. This will take about another 10 minutes. Add in the flour, stir and cook for about 7 more minutes. Mixture will become very sticky and dry. Cover with plastic wrap, and place in the fridge to cool while you make the pastry.
Shortcrust Pastry Dough: Preheat the oven to 350°F (180° C). Prepare a sheet pan lined with parchment paper. Cream butter and sugar together using an electric mixer until light; about 1 minute. Beat in egg yolks one at a time, until well combined. Add vanilla, salt and blend.
In a bowl whisk the flour and corn starch together. To the butter/sugar mixture, add in the flour and corn starch mixture until dough starts to come together, but dough is still a bit craggy, then knead gently with your hands to bring the dough together.
To form cakes: Take a tablespoon of dough and flatten out in your hand, set aside. Lightly butter your hands, and take a teaspoon of filling and roll it in your hands to form a ball. Place the flattened piece of dough in our hand, and place the ball of filling on top and fold over and bring the dough together to encase the filling. Roll the filled cake ball in your hands, to even out any seams. Shape the filled cake into an equal square. Place on a parchment lined baking sheet at least one inch apart, and bake at 350° F for 15 minutes on one side, then using a small offset spatula, carefully flip over and bake on the other side for 15 minutes more. They will turn lightly golden brown. Let the cakes cool completely on the baking sheet until cool to prevent crumbling. Eat when cool.