Preheat oven to 175 degrees C. Grease (or use Pam spray) a 9 inch (23 cm) round cake pan.
To prepare the topping, place the butter and brown sugar in a small saucepan and stir until the butter has melted and the sugar has dissolved. Allow it to cook for a few minutes without stirring until bubbles just start to appear around the outside edges of the mixture. The sugar will start to caramelise. Remove from heat and pour into the prepared cake pan. Spread the mixture evenly with a spoon. Arrange the pineapple slices on top of the sugar caramel and then place the cherries in each hole. Keep aside.
Next, to prepare the cake batter, sift the flour, baking powder and salt twice and keep aside.
In a large bowl beat the butter and sugar until light and fluffy. Scrape down the sides of the bowl and add the vanilla extract. Beat once and then add the egg yolks one at a time beating well after each addition.
Add the flour mixture in three parts alternating between milk in two additions (flour, milk, flour, milk, flour). Gently fold the mixture with a spatula once flour is added, do not beat.
In a separate bowl take the egg whites, add the cream of tartar to it if you are using it. It will help the egg whites achieve the fluffiness and hold firm peaks. But its optional. Beat the egg whites till stiff and add this mixture to the cake batter in two additions folding the batter gently as you add.
Pour the batter into the prepared cake pan and smoothen the surface.
Bake in the preheated oven for 45-55 minutes or until the top of the cake has browned and a toothpick inserted into the cake (not pineapple) comes out clean.
Remove from oven and place on a wire rack to cool for 10-12 minutes. Then use a sharp knife and run it around the edge of the pan and carefully invert the cake on to a serving plate or cake stand.
Cut and serve along with whipped cream or ice cream.