Preheat the oven to 340°F. Grease a mold, in this case, I used a pudding mold.

Prepare the caramel by heating the 8 tablespoons of sugar with the water in a bowl in the microwave for 3 or 4 minutes, or in a pan over low heat until it starts to caramelize. Pour the caramel into the mold.

Arrange the pineapple pieces previously cut to your liking, covering the entire surface of the mold, and now let's prepare the cake batter.

In a bowl, beat the eggs with the sugar until you get a slightly whitish cream. Add the oil, vanilla extract, and yogurt, and mix well until the ingredients are combined. Now add the oat flour along with the baking powder and mix until you get a well-integrated and creamy batter.

Gently cover all the pineapple pieces with the cake batter, level it, and bake for about 40 minutes.

Unmold immediately, with great care and patience. If any pineapple pieces remain in the mold, you can arrange them. If there's caramel left in the mold, pour it over the cake.

Tips:
*Don't let it cool because otherwise, it will be impossible to unmold this pineapple cake.
*You can replace the oil with melted warm butter, keeping in mind that you'll need about 5 tablespoons (about 70 grams) of butter.
*Poke the cake with a toothpick, without reaching the bottom of the mold, to check if it's well baked.