In a medium bowl, combine the melted butter and brown sugar with a fork until well blended.
Spred some extra butter on the bottom and sides of a 25 cm round cake pan, then pour the caramel mixture into the bottom of the pan. Then place the pineapple slices (without the syrup) and the cherries. If there are pineapple slices left over, cut them in half and arrange them on the sides of the pan or spaces left on the bottom.
For the cake:
Preheat the oven to 356º F (180° C). In a medium bowl, sift the flour with the baking powder and salt.
In a different large bowl, beat the eggs together with the sugar with an electric mixer or hand balloon for 5 minutes until the mixture lightens and triples in size.
Carefully add the pineapple syrup, oil and yogurt while continuing to beat. Beat for 30 seconds until everything is well blended.
Add the flour mixture in three separate additions. Beat only for a maximum of 30 seconds after each addition, just until the mixture is smooth and the ingredients are integrated so as not to overbeat.
Pour the mixture into the baking pan and bake at 356º F (180° C) for approximately 40-45 minutes until a wooden toothpick comes out clean.
Once ready, remove the cake from the oven and let it cool in the mold for 10 minutes. Afterwards, turn it out of the mold onto a plate and serve while still warm or at room temperature.