To make the filling

Cup of Yum
1. Dice pineapple into fine pieces. Place it in a large strainer over a large bowl for 10 to 15 mins. Let sit until most of the residual liquid is released. Drain and discard the liquid, and transfer the pineapple into a large saute pan. Add sugar and salt. Cook over medium heat. The pineapple will release a lot of liquid at first. Continue to simmer, stirring occasionally to avoid sticking, until all liquid evaporates completely and the pineapple pieces start to feel sticky. Add butter and stir to melt. Transfer everything to a medium-sized bowl. Let cool slightly. Then cover the top of the pineapple with plastic wrap. Let cool in the fridge completely before using.

For pastry

1. In a food processor (ideally) or by hand, add the flour, sugar, powdered milk and baking powder. Stir to combine.
2. Add the butter. Pulse or cut by hand until crumbly.
3. Add the egg and yolk. Mix until the dough just starts to come together. Transfer the dough onto a clean work surface. Form it into a rough square shape. Wrap in plastic and chill at least 30 mins, or up to overnight.

Shape the tin foil pan

1. Cut a large sheet of aluminum foil, about 2.5 feet (76 cm) in length. Fold in half 2 times, to form a thicker sheet that has 4 layers (so the pan will be sturdy enough to hold the pineapple cake). Place an actual loaf pan upside down (*Footnote 1). Press the folded foil over the bottom of the loaf pan to crease, shaping the foil like the loaf pan. Then remove the foil and fold at the creases, to create 4 sides that are about 1/2” (5 cm) high.
2. You can repeat this to create 2 foil pans so you can bake both pineapple cakes at the same time (highly recommended). Or you can bake one cake at a time by only using one pan (this will take a lot longer because each pineapple cake needs time to cool off before removing the foil).

Shape the dough

1. Once the dough is fully chilled, cut the dough into 4 equal pieces.
2. Place the dough between two large pieces of parchment paper. Roll out the dough until very thin and slightly larger than the foil pan, aiming to keep the shape of a rectangle.
3. Lift the top piece of parchment to release the dough. Carefully flip the dough sheet over, and remove the parchment paper from the other side. Carefully transfer rolled dough to the foil pan. Press the dough to fit the pan. The dough should come up on all sides. Trim the edge of the dough by pressing off any overhang with your fingers. You can patch up any tears with excess dough.
4. Fill the fitted dough sheet with half of the cooled pineapple filling. The filling should go almost all the way up to the top edge of the pan, with a little space left for the other dough sheet. Press lightly to smooth out the filling and form an even layer.
5. Repeat the rolling process with the next piece of dough using the same method from step 2. Place the rolled dough over top to seal in pineapple filling, trimming off any excess dough. Gently press the dough edges to seal the filling completely.
6. Preheat the oven to 325°F (163°C). Transfer the pineapple cake foil pans onto a sheet pan. Bake on the middle level for 20 to 25 minutes, until the top turns light golden. Let the pineapple cakes cool off completely. Then you can fold down the edges of the foil pans and place the pineapple cake on a cutting board. To cut the pineapple cake, slice lengthwise down the center. Then slice into thirds crosswise, then slice each third in half to make 12 pieces in total.